Magpies ruin Keegan's homecoming
Keegan received a rapturous reception from the fans who idolised him both as a player, and manager, on Tyneside but he was unable to mastermind the outcome he desired as City valiantly bowed out of the competition against Premiership title-chasers Newcastle.
Solano's 59th minute goal separated the teams, and booked The Magpies' quarter-final berth, as City were forced to play over an hour with a man short following Richard Dunne's sending off.
With the two sides rightly regaled for their commitment to attacking football, the match had even the neutrals licking their lips in the salivating prospect of an entertainment feast.
The early exchanges appeared to confirm the pre-match hype as both teams went for the jugular with Danny Tiatto blazing a volley wide, and Alan Shearer thundering a drive just wide of the post.
But that proved to be a false dawn as, somewhat unusually for the two teams on display, it was defences that were on top.
Though The Magpies enjoyed the lion's share of possession, they were profligate in its usage as all too often the final ball was awry.
On the occasions the hosts did provide a quality pass, jet-heeled striker Craig Bellamy was caught offside. Like an Olympic sprinter trying to jump the gun, there was always only a hair's width in the decisions but the ebullient Welshman could just not trigger the offside trap to precision.
It was a first half devoid of genuine goalscoring chances and the only save made was by Nicky Weaver midway through the period when he pushed out Laurent Robert's stinging volley.
The 28th minute provided the greatest talking point of the opening half when City's Republic of Ireland defender Dunne was given his marching orders.
For the only time in the half, Bellamy timed his run to perfection and as he scampered towards goal, Dunne persisted in tugging his shirt back before The Magpies man tumbled to the turf fractionally outside the area.
Referee Alan Wiley had little alternative but to show Dunne the red card for what was one of the more blatant professional fouls witnessed this season.
Newcastle did have the ball in the back of the net three minutes before half-time but Bellamy's cool finish was irrelevant as he was adjudged to have been offside.
In injury-time the best chance of the half fell to the visitors after Darren Huckerby played a one-two with Eyal Berkovic.
As the former Magpie charged towards the corner of the box, keeper Shay Given came recklessly racing off his line but Huckerby's side-foot drifted agonisingly wide.
City boss Keegan shuffled his tactics at the interval, replacing Huckerby with Richard Edghill and moving Shaun Wright-Phillips further forward.
The first chance of the half fell at the feet of the diminutive Wright-Phillips as he latched on to Berkovic's incisive through ball but his shot was saved by Given.
Inside St James' Park, the volume was cranked up a notch and it precipitated an increase in the excitement level on the pitch as Newcastle almost forged ahead on 55 minutes.
Bellamy's square ball inside the box found Aaron Hughes at full stretch six yards out but he was thwarted by Weaver.
If Weaver was at the rescue on that occasion, he was completely at fault four minutes later when The Magpies snatched the lead.
Gary Speed's cross-field ball was chased down by Solano after the Peruvian tangled with Niclas Jensen.
Solano poked it beyond the onrushing Weaver, who was hopelessly out of his goal, and then rolled it into the empty net.
City refused to lie down, though, and warmed to the arduous task of trying to salvage their cup dreams.
Berkovic was having an increased influence in midfield as Wanchope started to torment the home defence.
The bandy-legged Costa Rican saw one shot deflected over the bar, and from the resulting corner, Kevin Horlock glanced wide with City ruing not having someone gambling at the far post.
Moments later and Berkovic fed Wanchope but Given was equal to his shot.
The visitors continued to apply the pressure with the home rearguard becoming evidently more uncomfortable with each passing attack as Keegan's troops made light of their numerical disadvantage.
With 15 minutes left on the clock, Newcastle had a gilt-edged chance to put the tie beyond their opponent's reach after an error by Paul Ritchie.
Solano teed up Bellamy eight yards out and as he twisted to shoot, Weaver blocked the effort with Shearer remonstrating with his team-mate for not laying the ball off.
Newcastle almost doubled their advantage two minutes later when Solano's impudent shot with the outside of his right boot curled wide.
With two minutes remaining, Newcastle nearly carved out a freak second when Clarence Acuna's shot from Lomano Lua Lua's cross was deflected just wide of the upright.
From the resulting corner Speed's header was cleared off the line, and with City unable to hack the ball from danger, Bellamy's volley was superbly saved by Weaver.
In the dying seconds, Bellamy avoided being caught offside but after rounding Weaver, his low shot was scrambled off the line.
Click on the link below for a match summary:
Newcastle 1-0 Manchester City
Click here for the Opta quick stats.