The Europa League semi-finals beckon but Slavia Prague could so easily have taken advantage of Chelsea ’s complacency.
Maurizio Sarri’s men somehow allowed a 4-1 lead - built up after just 26 minutes - to slip after looking as though they could score as many as they liked.
Instead, during three madcap second-half minutes, Czech midfielder Petr Sevcik hit two long-range efforts - one an absolute screamer - to leave Stamford Bridge stunned and the tie on a knife-edge.
Had Sarri blown this one he really would have been bang in trouble. As it is, you wouldn’t bet against Chelsea now winning the Europa League and returning to the Champions League.
They’ll fancy their chances against Eintracht Frankfurt who staged a comeback to beat Benfica.
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But Sarri said afterwards: “As usual in the last two months, we started very badly in the second half.
"We need a solution. We need to solve this problem. In the last 10 matches, we started like in this match (in the second half). It's a big problem.
“I can try not going into the dressing-room at half-time. I can try if that'll solve the problem!”
Chelsea are surely one of the most dysfunctional teams in Europe. They spend most of the season mired in chaos, confusion and controversy yet when all is said and done they tend to end up with silverware.
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They are now the first English side to win 11 major European games in a single season. For the current campaign their record reads: Won 11, drawn one. So no-one of a Chelsea persuasion will be afraid of Eintracht, Arsenal or Valencia.
The goalfest began after just five minutes. Pedro played a one-two with Olivier Giroud and lifted the ball over keeper Ondrej Kolar.
Four minutes later it was 2-0 after Giroud held the ball up for Eden Hazard. The Belgian squared it to Pedro and his effort went in off defender Simon Deli.
Midfielder Tomas Soucek buried a free header from a corner on 25 minutes for 2-1 but it still looked way too easy for Chelsea.
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Easy became embarrassing two minutes later when Emerson crossed, Giroud’s shot was saved and Pedro turned home the rebound. We hadn’t yet played half an hour.
In the second half, however, Sevcik beat Kepa with a low piledriver six minutes after the break.
The Czech midfielder repeated the feat with a diagonal screamer three minutes later, Stamford Bridge left relieved at the final whistle.
Sarri added: “We now need to think about the semi-final and study the opponents. We want to get to the final and win it, but Eintracht are a great team.”
