Enzo Maresca admits worries as Chelsea scrape through in Geneva

Following a 2-0 first-leg victory a week ago, Christopher Nkunku's early penalty extended the Blues' lead in the tie to seemingly extinguish any hope the Swiss side had of pulling off a surprise result.

But thereafter things went awry for Maresca as Servette hit back with two goals to stun his team, first when Jeremy Guillemenot drilled past Filip Jorgensen to level things on the night before half-time then again when Enzo Crivelli headed in to set up a nervous finish.

"I think the first half an hour was comfortable and we had three or four chances to make it 2-0," said Maresca, whose team will find out their six opponents in the tournament's revamped league phase at Friday's draw in Monaco.

"Then we concede the goal and it's normal to suffer a little bit.

"I was very worried about this game. For (Servette), it's probably their biggest game of the season. This kind of game, you have many things to lose and not many things to win. This is why I was so worried yesterday and before the game."

Chelsea fielded a much changed starting XI from the side that beat Wolves 6-2 on Sunday.

"It's a competition that we are going to try and do our best in," said Maresca. "The team, the way we started, the team was there and then we conceded, they had some chances and then we lost a little bit of confidence."

There was a senior debut for 18-year-old winger Tyrique George who came off the bench in the second half.

"He was good," said Maresca. "He was not shy. He had personality. We also had (18-year-old defender) Josh Acheampong on the bench. Unfortunately (16-year-old Ollie) Harrison was not on the bench. It's important to build something with the academy players."

There was also a first appearance for Noni Madueke since his England call-up earlier on Thursday, fresh from scoring a hat-trick in Chelsea's thumping win at Molineux.

"Very happy," said Maresca. "The important thing for (Madueke) is to not drop anything and keep working hard."