Rangers' unbeaten league run of 40 games was ended at Tannadice, with Dundee United claiming a hard-fought 1-0 victory in the Scottish Premiership.
Thomas Courts' United side enjoyed a positive first half, although Rangers had the best openings as the returning Alfredo Morelos and James Tavernier both went close.
Steven Gerrard's half-time team talk seemed to have done the trick as the reigning Scottish Premiership champions dominated after the break, but soon found themselves behind.
There was a slice of luck to Dundee United's 64th-minute goal as Adrian Sporle's pass took a nick off Steven Davis on the way through, but the continued run and cool finish of Jamie Robson saw the hosts impressively ahead against the run of play.
Rangers almost equalised soon after as Connor Goldson directed a header wide, but there was ultimately no response from the visitors as Dundee United fiercely defended their lead, with Rangers suffering their first league defeat since losing to Hamilton on March 4, 2020.
It will go down as a famous victory for Dundee United as Courts registered his first win as manager on his home debut. Rangers must now regroup ahead of a vital Champions League third-round qualifier second leg against Malmo at Ibrox on Tuesday.
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How Rangers fell to a spirited Dundee United
Dundee United were positive and energetic from the first whistle, but it was the Scottish Premiership champions who had the first clear-cut effort. Joe Aribo showed off some superb skill to wriggle through a packed box, cutting the ball back for the returning Morelos, but the striker lifted his effort over the bar.
Rangers soon began to control the match, though, and it was the striker who again went close just before the half hour, sniffing out a yard of space at the back post from a deep cross from Ryan Kent off the left flank. However, Morales could not direct his header on target as it rifled wide.
Dundee United: Siegrist (7), Edwards (7), Mulgrew (7), Fuchs (7), Smith (6), Harkes (6), Butcher (6), Clark (6), Robson (8), Pawlett (7), Chalmers (6).
Subs used: Sporle (7), Watson (n/a).
Rangers: McLaughlin (6), Tavernier (7), Goldson (7), Helander (7), Barisic (6), Kamara (6), Davis (6), Lundstram (6), Aribo (6), Morelos (6), Kent (6).
Subs used: Wright (6), Itten (n/a), Defoe (n/a).
Man of the match: Jamie Robson.
Dundee United tested Rangers when their chances came. They had a good effort from a free-kick, but Charlie Mulgrew fired an effort wide - much to the relief of Jon McLaughlin as the ball slipped through his hands. At the other end, Tavernier just lifted a free-kick over the crossbar from 25 yards out, but only by inches.
- Lawrence Shankland was not included in Dundee United’s squad, suffering with a hip knock. However, there has also been speculation surrounding his future at the club.
- Rangers welcomed Alfredo Morelos back into their XI after competing in the Copa America with Colombia. Jon McLaughlin, Glen Kamara and Joe Aribo also came back into the starting side from Tuesday’s game against Malmo, replacing Allan McGregor, Scott Arfield, Scott Wright and Cedric Itten. Kemar Roofe missed out due to family commitments.
There was incessant pressure from Rangers at the start of the second half, with their best opening coming in the 57th minute. Tavernier took a good first touch from a cleared corner, before lifting a superb effort goalwards, but Dundee United goalkeeper Benjamin Siegrist pushed it away at full stretch.
Having had no shots after the break and being pegged back deep in defence, Dundee United took an unlikely lead just after the hour. It was a neat passage of play between Robson and Sporle, with the former continuing his run as he received the return pass - albeit with a deflection off Davis on the way through. Robson then showed wonderful composure to slot home past McLaughlin.
Rangers had only gone behind first in four games last season - winning one and drawing three - and attentions immediately turned to a Rangers response. They almost equalised not long after, but Goldson just flicked a header wide from a Tavernier corner as the clock continued to tick down.
The visitors dominated the ball but were met by a Dundee United side who were resolute in their defending. Tavernier went close again late on, but could only slice Borna Barisic's cross behind, and, after a heart-stopping five added minutes, the home side saw out their victory to end Rangers' history-making unbeaten run.
Man of the match - Jamie Robson
Robson was a vital part of Dundee United's victory. Let's start with the day job - he was superb at left-back. When Rangers were dominating at the start of the second half, Robson was there every time to block and defend.
But it was his continuous run for the goal which was truly impressive, combining well with Sporle down the flank. The composure to slot home and send McLaughlin the wrong way was superb.
His stats were also impressive too - Robson topped the match stats for possession gained (13) and joint top for interceptions (3), and had the most touches (70) and passes (36) in the Dundee United side.
Former Dundee United midfielder John Rankin told Sky Sports: "Defensively he was assured, he was strong in the tackle, strong in one v one situations, he was never exposed. Going forward, he caused problems. He took the winger back up the pitch, and in the first half especially, he put umpteen balls in the box.
"For the goal, it's OK getting there but he had the composure to put it past the goalkeeper. I thought he was outstanding today."
What the managers said
Dundee United head coach Thomas Courts told Sky Sports: "I had a weird feeling this week that we could actually win this game. I don't know where it came from and I didn't want to mention it to anyone either in case it made me look foolish after last weekend but I had a sneaky suspicion we could perform this week and thankfully we did that.
"It's a monumental victory. We took a bloodied nose last week but some of the ideas we tried to implement came to the fore today. Perhaps we were better off for what we experienced at Aberdeen. It was a colossal performance.
"When you play against a team of their quality, you know you have to defend well as a team. We managed to get the crowd onside today and it was a brilliant spectacle today."
Rangers manager Steven Gerrard told Sky Sports: "From our point of view, it was not good enough. I think over the course of the 90 minutes we didn't deserve to lose the game but you always put yourself in that position if you don't score goals.
"We didn't create enough today and whilst the game is at 0-0 there's always a risk if you get one or two things wrong. The result and the performance is on me and my team. We'll have to accept that and move on pretty quickly.
"I've got belief and confidence in all of my attacking players but that's when we're at our best. Credit to Dundee United for defending well.
"When you suffer a setback, it gives you the chance to re-set and give some of the players some home truths. We'll go away and analyse the game. At the moment, we've not got time to feel sorry for ourselves [with the Malmo game on Tuesday].
"We're going to need a far better level of performance to get that done."
'Rangers were beaten by the better side'
🗣️"This is Dundee United's day. Rangers were beaten by the better team."— Sky Sports Scotland (@ScotlandSky) August 7, 2021
Kris Boyd reacts to the result at Tannadice and insists one Ibrox player has "a lot to improve on". What did you make of the game?
📺Reaction & analysis live on Sky Sports Football pic.twitter.com/xnuv7jffvp
Sky Sports' Kris Boyd:
"Rangers were beaten by the better team today. They can speak about having ball possession but they were far too slow with it. They switched off at key moments.
"John Lundstram switches off for the goal. I know it's early doors, but he's got a lot to improve. We've seen big names come up here and struggle in the past and he's going to have to up his game. This is Dundee United's day.
"Right from the start, they were aggressive, they were right in Rangers' face, stopped them playing and they well and truly deserved the three points today.
"Steven Gerrard touched on it after the game against Malmo on Tuesday night, that there were six of seven that had to buck up their ideas basically, and that will do them no good today because some of them were way off it again today.
"Dundee United's game plan today was to sit and be difficult to break down and they were excellent. You've got to give a lot of credit to the manager and the staff because you can tell that's a well-drilled team."
Rangers face Malmo in the second leg of their crucial Champions League third-round qualifier on Tuesday at Ibrox (kick-off 8pm) before hosting Dunfermline in the second round of the Scottish League Cup on Friday (kick-off 7.30pm).
Dundee United travel to take on Ayr United in the Scottish League Cup next Saturday at 3pm.