Aberdeen’s title challenge was dealt a major blow as Motherwell came from behind to defeat the Dons 2-1 at Fir Park.
Kenny McLean netted his seventh goal of the season from the penalty spot to give Derek McInnes’ side a half-time lead.
But two quick-fire goals from Scott McDonald and Louis Moult gave the Steelmen a fifth win in six games, leaving the Dons four points behind Celtic having played one game more.
Aberdeen ended the match with 10 men after Barry Robson was sent off only a minute after entering the play for a reckless challenge on McDonald.
The Dons made one change from the team that defeated Kilmarnock 2-1 with Mark Reynolds returning to the team in place of Robson.
Mark McGhee’s side were unable to train from Sunday to Thursday because so many players were laid low by illness and the Motherwell manager admitted he felt at one stage that the game would be called off.
Despite the apparent pandemic at Fir Park the hosts made only three changes from the team that won 2-1 against Dundee United with Morgaro Gomis, Kieran Kennedy and Jack Leitch replacing Ben Hall, Keith Lasley and Stephen Pearson.
Tom Rogic’s dramatic late winner for Celtic against Kilmarnock in the lunchtime kick off meant the Dons went into the matching four points behind the Scottish Premiership leaders.
The game’s first chance fell to Aberdeen captain Ryan Jack but his low drive from the edge of the area was well handled by Connor Ripley.
Simon Church was next to threaten for the visitors but he dragged his shot from 12 yards out just wide.
Both sets of supporters joined in a minute’s applause in the 16th minute for young Dons fan James Stewart who died from cancer earlier this week.
There was a worrying moment for the Dons when Graeme Shinnie required treatment but the former Caley Thistle captain, who was playing in the centre of midfield, managed to play on.
Motherwell’s first chance arrived after 21 minutes with Marvin Johnson volleying over from a Leitch cross.
The Steelmen almost took the lead 10 minutes later when Scott McDonald laid the ball off perfectly for Louis Moult whose powerful strike cannoned off the post with Scott Brown beaten.
But it was the Dons who made the breakthrough a minute before the break.
Hayes’ rampaging run into the Motherwell penalty area was brought to an abrupt end by Kieran Kennedy’s poorly timed challenge, giving referee Don Robertson no option but to point to the spot.
McLean took the spot-kick responsibility and calmly sent Ripley the wrong way to open the scoring.
The Dons went close to doubling their lead after the break with McLean drawing a fine save from Ripley before Simon Church clipped the crossbar from the resulting corner.
But it was Motherwell who were to net the crucial next goal.
McDonald profited from some hesitant defending from the Dons, heading over Brown from close range after the Dons failed to deal with a Johnson cross.
And two minutes later the hosts were in front.
Again it was courtesy of some poor defending with Moult capitalising on a mix-up between Brown and Reynolds to lob the ball home.
Aberdeen’s misery was compounded soon after when substitute Robson was sent off for a poor challenge on former Celtic teammate McDonald.
