Rangers eased through to round four as Motherwell were shocked at St Mirren.
Rangers had few problems reaching the fourth round of the Scottish Cup as Kris Boyd grabbed a hat-trick on his debut in their 5-0 victory over Peterhead.
The striker (pictured) scored his first goals since joining from Kilmarnock in the second half after Sotirios Kyrgiakos had finally broken the deadlock on 35 minutes.
Substitute Ross McCormack rounded off the scoring with a fifth on 75 as the visitors from Division Two were unable to cause an upset at Ibrox.
Aberdeen staged an impressive comeback in the top-flight tussle against Dundee United as they came from two goals down at Tannadice.
A double from David Fernandez in the first half seemed to have put the hosts' name in the draw for the next round.
However two goals in the space of five minutes from Stephen Crawford levelled the tie up and Barry Nicholson notched the winner on 79 minutes.
The other all-Premier League tie saw Hearts come out 2-1 winners against Kilmarnock thanks to goals from Steven Pressley and James McAllister. Colin Nish netted a late consolation for Killie.
Edinburgh rivals Hibernian are also through to the next round after they trounced Arbroath 6-0 at home, Scott Brown scoring a goal in each half in the one-sided result.
Ivan Sproule, Michael Stewart, Garry O'Connor and Steven Fletcher also got on the scoresheet as Tony Mowbray's team enjoyed a comfortable afternoon's work.
Non-league outfit Spartans produced the first shock of the round when they edged out Queens Park in a five-goal thriller.
The Third Division side took an early lead in the lunchtime kick-off through Alan Trouten but Bob Mitchell levelled matters just before half time.
Jon Seeley and Donal Henretty then gave Spartans a 3-1 lead and despite David Weatherston cutting their lead in half, the home team managed to hang on for victory.
Aidrie were also surprise winners in the third round as two late goals meant they upset Premier Division side Dunfermline 4-3.
Stephen Docherty's second goal of the game in injury time won the match after Stephen McKeown's penalty on 89 had levelled the match up.
Gary Mason and Noel Hunt had earlier given the home club a 2-0 lead before Docherty and Martin Hardie got Aidrie back on level terms. Derek Young got Dunfermline's third goal, but it was not enough as they suffered a late collapse in front of their own fans.
Motherwell were another top-flight team to be dumped out at the third round stage as they were thumped away at St Mirren.
Charlie Adam scored two of the goals for the runaway Division One leaders and John Potter also found the net in a surprisingly comfortable win.
Livingston were indebted to a late equaliser away at Alloa, who currently sit at the bottom of the second division, as Richard Brittain's injury-time goal cancelled out Michael Bolochoweckjy's opener.
Inverness and Ayr will both be in the hat for the fourth round draw after a 1-1 result at Caledonian Stadium.
Rory McAllister put the home side 1-0 up but their advantage lasted less than a minute as Gareth Wahdelaw immediately replied for Ayr.
Derek Lyle's 81st minute goal meant Queen of the South will have a replay against Hamilton after Academical had hit the front through Mark McLaughlin just after half time.
Division One high-fliers Ross County had little trouble against Forfar, Don Cowie scoring twice and Alex Burke, Sean Higgins and Kevin McKinlay also finding the net in a 5-0 romp.
Alan Gow scored a goal in each half to see Falkirk to a 2-1 win over Brechin, whose goal came from Charlie King just before the hour mark.
Steve Tosh's strike on 12 minutes was enough to give Gretna a 1-0 success away at St Johnstone, while Paul Ritchie grabbed the only goal of the game for Partick as they beat Stirling Albion by the same scoreline.
Spartans 3-2 Queen's Park
Alloa Athletic 1-1 Livingston
Dundee United 2-3 Aberdeen
Dunfermline Athletic 3-4 Airdrie United
Falkirk 2-1 Brechin City
Hearts 2-1 Kilmarnock
Hibernian 6-0 Arbroath
Inverness Caledonian Thistle 1-1 Ayr United
Queen of the South 1-1 Hamilton Academical
Rangers 5-0 Peterhead
Ross County 5-0 Forfar Athletic
St Johnstone 0-1 Gretna
St Mirren 3-0 Motherwell
Stirling Albion 0-1 Partick Thistle
