Champions Celtic were left three points clear at the top of the Scottish Premier League on Sunday after Glasgow rivals Rangers slumped to a 2-1 defeat at the hands of Dundee United.
Eight days after beating Celtic 3-0 and five days after holding Barcelona to a goalless draw in the UEFA Champions League, Walter Smith's side were lacklustre as they were beaten for the third time in the league this season.
The win, which lifts Dundee United into a share of second place in the table, was thoroughly deserved for Craig Levein's revitalised side, who had taken the lead through Lee Wilkie's first-half strike.
Rangers got back on level terms seven minutes after the restart, Daniel Cousin scoring from the spot after Christian Kalvenes had brought down DaMarcus Beasley in the box.
But it only required a further two minutes for the home side to reclaim their advantage. Spanish centreback Carlos Cuellar was penalised for a foul on Jordan Robertson and Barry Robson slotted in the penalty.
Wilkie's opener proved to be the highlight of the encounter, the striker finishing off a Willo Flood free-kick with an impressive volley at the back post.
Smith refused to blame the setback on the physical hangover from Tuesday night's exertions in chasing after Ronaldinho and the rest of Barcelona's superstar line-up.
"The European game had nothing to do with it," Smith insisted. "The players had plenty of time to recover from the game on Tuesday night. It certainly wasn't tiredness and we saw that in the second half."
The former Scotland boss added: "In the first half it was a quiet start from both sides and it was disappointing to lose the goal we lost in terms of defending at a set-play.
"In the second half we stepped up, applied some pressure and got back on level terms. Then we shot ourselves in the foot by giving away a penalty. It was disappointing to lose a game that we put a lot into."
Levein was delighted to mark one year in charge at Tannadice by repeating the 2-1 win over Rangers with which he announced his arrival at the club. "The scoreline was the same as it was a year ago but today's result doesn't tell the real story - Rangers are a vastly improved team now and we needed to be too," Levein said.
"The players did everything I asked of them and, in some cases, a little bit more."
In Sunday's other game, a disappointing week for Aberdeen ended in frustration as they followed their 3-0 UEFA Cup defeat to Panathinaikos with a 1-1 draw at home to Falkirk for whom Patrick Cregg cancelled out Scott Severin's first-half penalty.
Celtic returned to winning ways on Saturday when a hat-trick from Australian striker Scott McDonald secured a 3-0 win over his former club Motherwell.
But Hibernian's early season momentum was halted by a 1-0 home defeat by St Mirren, a setback which means John Collins' side slip to fourth in the table.