It is no secret that Chelsea’s interim manager Rafael Benitez loves to rotate his players, but it almost came back to haunt him as his side scraped through to the Europa League semi-finals.
Chelsea should have cruised through to the last four after going to Moscow with a two-goal advantage and taking the lead twice during the second leg. However, they ended up greeting the final whistle with a huge sigh of relief after conceding three goals in a frantic second half.
Fatigue is the club's greatest opponent as they challenge on three fronts and Benitez has been making changes match-to-match to cope with it. His team selection betrayed just how much he had Sunday's FA Cup semi-final with Manchester City on his mind.
On the bench were Chelsea's most creative trio Juan Mata, Eden Hazard and Oscar. More significant was 18-year-old Nathan Ake in front of the back four in what appeared to be a change from the normal 4-2-3-1 to a 4-1-4-1. It was just the second start in Ake's professional career, but the Dutchman showed why he is so highly rated with an assured display.
There seemed no cause for alarm when Fernando Torres put Chelsea in front inside five minutes. John Obi Mikel may not like the Europa League, but Torres must wish he could play in it every week. After two goals in the first leg last week, following one in the last round against Steaua Bucharest, he made it four in three games with a fine lob to put Chelsea on course.
The tie was switched to Moscow because Kazan's pitch is frozen, and playing at a neutral venue certainly worked in Chelsea's favour. Thousands of empty seats greeted them rather than boos and even the harshness of Moscow's winter had eased in the past few days to ensure the game was played in the kind of temperatures they have experienced at home.
Chelsea coasted through the first half but were given a warning just before the break when keeper Petr Cech had to save smartly from Gokdeniz Karadeniz.
Then David Luiz and Frank Lampard started arguing with each other and the tone for the second period was set. Benitez played down the significance of their row afterwards. "It's always good to have players arguing about things that happen on the pitch, so you can correct these things at half-time," he said. "We were talking about that [in the dressing room], adjusting positions, so it's fine. Not a problem."
However, the second half was a woeful display from the away side and on another night they could have been flying back to London after a dismal exit. Ivan Marcano was the first to take advantage of slack defending to head home a corner just six minutes after the restart. Victor Moses appeared to ease any nerves when he struck soon afterwards, but the calamities in Chelsea's back four continue. Captain John Terry, who was making his 100th appearance for the club in European competition, did not appear to enjoy his return to the ground where he missed a spot-kick that would have won Chelsea the Champions League against Manchester United in 2008.
But when Rubin captain Karadeniz levelled the scores on the night by heading past Cech, they still needed three more to progress. But first Marcano headed against the post, and then there was real cause for concern as Cesar Azpilicueta was judged to have pushed Aleksandr Ryazantsev in the area, although it looked like a dive.
Bebras Natcho converted the penalty to make it 3-2 and 5-4 on aggregate, and things could have got even worse if Jose Rondon hadn't headed straight at Cech from just four yards.
So Chelsea are in tomorrow's draw for the last four, but they weren't convincing and Manchester City will look forward to Wembley with relish.
Man of the match Eremenko.
Match rating 7/10.
Referee F Aydinus (Tur).
Erkin strike helps Turks make history
Fenerbahce reached a European semi-final for the first time in their history after holding Lazio to a 1-1 draw, progressing to the last four 3-1 on aggregate.
Senad Lulic converted Antonio Candreva's cross on the hour to give Lazio brief hope, but Caner Erkin's equaliser took the Turkish side through.