Chelsea coach Luiz Felipe Scolari found out the hard way that tinkering with a winning side is not always a good idea as the Blues crashed out of the Carling Cup 5-4 on penalties to Coca-Cola Championship side Burnley.
Scolari left six regular first-team players out of his starting line-up and then watched Burnley reach the quarter-finals in a dramatic penalty shoot-out after the match finished 1-1 after extra-time.
Captain John Terry, John Mikel Obi, Frank Lampard, Petr Cech, Jose Bosingwa and Nicolas Anelka were all rested although Lampard and Obi were both pressed into action off the substitutes' bench.
However, Scolari did not regret his decision to ring the changes for the fourth-round tie.
‘The players are disappointed because they lost a competition,’ said Scolari.
‘They wanted to win this game but now it is time to work for Saturday's game.
‘We had all the information about Burnley to win the game. But what happened is similar to other games and we made many mistakes in front of goal.
‘If we had had more quality in front of goal we would have won this game.
‘I kept some players out because they have played a lot of games but it was still a side that could have won this match.
‘We have lost one competition. This is not normal for us. We want to win all the competitions but we have lost one and we need to understand this.
‘I am not angry with the players because they tried their best. If they make mistakes maybe it is because I have not given them good lessons. The players tried to do their best.’
But Scolari's tactics will surely come under scrutiny after a defeat that was also marred by an incident involving returning striker Didier Drogba.
He put the Blues in front in the 27th minute with his first of the season but could face a Football Association charge after throwing an object back into the crowd as he tried to celebrate.
Drogba has since apologised for his actions but Scolari's decision to remove him from the action just before Ade Akinbiyi's shock 70th-minute equaliser, had costly repercussions.
Drogba's replacement, Franco Di Santo, was forced off with a hamstring injury in extra-time leaving Chelsea, who had used all their subs, to finish the game with ten men.
The tie ended 1-1 after extra-time but Burnley goalkeeper Brian Jensen, nicknamed 'The Beast' by his team-mates because of his size, saved spot-kicks from Wayne Bridge and Obi to dump the Barclays Premier League leaders out of the competition.
Scolari also lost midfielder Deco at half-time with a minor injury but the Brazilian coach hopes to have him back for Saturday's trip to West Brom.
