Nottingham Forest slipped to a controversial 3-2 defeat against Southampton at St. Mary's Stadium.
Rickie Lambert gunned down Forest with a hat-trick but The Reds were left fuming after having strong claims for a penalty waved away by referee Iain Williamson.
The official ignored Forest's appeals for a spot-kick despite goalkeeper Kelvin Davis appearing to bring down Matt Derbyshire just moments before Lambert grabbed what proved to be the winner.
It was tough on Forest who produced a vastly improved performance 13 days after their home defeat by West Ham.
Derbyshire, a summer signing from Olympiakos, bagged his first goal for the club to give Forest an early lead on the south coast.
But Southampton, who were in second place in the Championship at the start of the game after a scintillating start to the season, came storming back.
They seized the initiative with two goals from Lambert but Radi Majewski scored before half-time to haul McClaren's men level. That looked like earning Forest a richly deserved point before Lambert's late show.
Forest went into the game without injured quartet Robbie Findley, Marcus Tudgay, Paul Anderson and George Boateng but Guy Moussi made his first appearance of the season after recovering from a calf problem.
And they got off to the perfect start, taking the lead after just seven minutes as Derbyshire opened his goal account for the club.
Ishmael Miller was the architect of the goal as he showed great awareness with a cross from the left that Derbyshire converted from close range.
But Southampton hit back almost immediately as they capitalised on slack defensive work by The Reds.
Guly Do Prado was given too much time and space to pick out David Connolly in the area and after his shot had been blocked by Lee Camp, Lambert was on hand to fire in the equaliser.
Wes Morgan and Chris Gunter made great blocks to deny Dean Hammond and Connolly respectively, while Lambert went close with a free-kick from just outside the area as The Saints went in search of a second.
They didn't have to wait too long to edge in front as Lambert poached his second of the game in the 25th minute by heading in at the back post after Connolly had flicked on Jack Cork's cross from the right.
With Forest reeling Camp had to be alert to keep out a Jose Fonte free header from a Danny Fox free-kick.
But The Reds regained their composure and after Miller had had appeals for a penalty waved away and Derbyshire had headed over the bar they drew level.
Again Miller was at the heart of the approach play, finding Derbyshire in the area who calmly picked out the unmarked Majewski who levelled matters from eight yards out.
Forest went close to retaking the lead before half-time with a well-worked corner routine. Reid found Majewski on the edge of the area and his half-volley fell nicely for Luke Chambers whose header was deflected narrowly wide.
It took a stunning save by Kelvin Davis to keep out Miller's header from a Cohen free-kick at the start of the second half.
Adam Lallana tested Camp with a shot from just outside the area but the Forest No.1 palmed his effort away for a corner.
At the other end, Miller again made a nuisance of himself in the home side's area as he tried to get on the end of a Cohen pullback but Southampton managed to scramble the ball clear.
Fonte went close to restoring The Saints' lead as he headed against Camp's left-hand upright from a corner, while the Northern Ireland international 'keeper made a smart save to keep out a powerful long range shot from Morgan Schneiderlin.
Lallana wasted a golden opportunity to restore Southampton's lead 13 minutes from time as he fired well wide of the target after Camp had only managed to parry a Lambert free-kick.
Forest were furious when referee Williamson rejected their penalty appeals eight minutes from time.
Instead Derbyshire was booked and within 60 seconds Southampton snatched the winner as Lambert headed home his third goal from a Fox free-kick.
Forest: Camp, Cohen, Morgan, Chambers(C), Gunter, Majewski, Greening (McGugan 87min), Moussi (Lynch 78min), Reid, Derbyshire, Miller (McGoldrick 65min)
Subs not used: Smith, Moloney
Bookings: Moussi 26min, &nbsp;Gunter 34min, Derbyshire 81min, Lynch 90+4min
Scorers: Derbyshire 7min, Majewski 43min
Southampton: Davis, Cork, Fonte, Hooiveld, Fox, Do Prado (Chaplow 68min), Hammond(C), Schneiderlin, Lallana, Connolly (De Ridder 80min), Lambert
Subs not used: Bialkowski, Martin, Dickson
Bookings: Connolly 34min, Cork 51min, Lambert 84min
Scorer: Lambert 9min, 25min, 83min
Referee: I Williamson
Attendance: 24,784 Away attn: 1,777