Chelsea drew 1-1 with Eintracht Frankfurt in their Europa League semifinal first leg on Thursday with Pedro grabbing a crucial away goal for the London club on the stroke of half-time.
The draw meant Chelsea set a record of 16 successive matches unbeaten in the Europa League, breaking Atletico Madrid's mark from 2011-12.
Chelsea manager Maurizio Sarri left Eden Hazard on the bench until the 62nd minute, preferring to rest the Belgian forward for the important Premier League games against Watford and Leicester City in the final weeks of the season.
Serbian Luka Jovic put the hosts ahead after 23 minutes, stooping to head past the outstretched Kepa Arrizabalaga off a cross from compatriot Filip Kostic and raising the decibels in a stadium famed for its atmosphere.
The goal was the 21-year-old's ninth of the competition and 26th this season, but Frankfurt failed to press home their advantage, running out of energy in a second half dominated by the visitors.
Ruben Loftus-Cheek blasted just wide in the 42nd minute and fed the ball through the Frankfurt defence to Spanish winger Pedro who hammered in a low left-footed shot right before the break.
"We were a bit in trouble," Chelsea captain Cesar Azpilicueta said. "I think the last 15 minutes of the first half we dominated with great chances. We scored the goal before halftime and in the second half I think we had more chances than them."
Chelsea were far livelier after the break -- in a reversal of the first 40 minutes -- with the hosts having a close escape when David Luiz rattled the crossbar from a 55th minute free kick.
Sarri said Hazard started on the bench because of a recent heavy workload.
"Eden was on the bench because, in the last period, he played 10 matches in a row. It's impossible to play that many. For us, this was match No. 59 I think, and Hazard also played eight matches in the national team. For a player, it's impossible to play 70-75 matches in a season. And so, sometimes, Hazard like all the other players needs to rest. Or not to rest, but not to play for 90 minutes.
"This is the first reason. The second is that Eden usually is able to change the match from the bench, and so, for me, it was better to start with Willian and then to try, in the last 30-35 minutes, with Eden. But for Eden, it's impossible to play 75-80 matches in a season."
Both sides are fourth in their domestic leagues, with the Europa League offering an alternative route to next season's Champions League.
"We have to play five matches in two weeks with the same level of importance. We don't know at the moment which is the right way [to qualify] because we can get into the Champions League by the Premier League or by the Europa League,"Sarri said. "At the moment, we don't know the right way. But we want both.
"We want the top four in the Premier League, and we want to reach the final. But we don't want to play the final this time; we want to win the final. It's very difficult because we have to play again in the Premier League in 62 hours, so it's not easy to recover, especially in a very competitive championship like the Premier League. You risk to pay."
The second leg is at Stamford Bridge May 9 with a spot in the final on the line.