LONDON-Marcos Alonso’s late header secured Chelsea a 1-0 win at Slavia Prague while Arsenal cruised to a 2-0 victory over Napoli at the Emirates Stadium.

Aaron Ramsey gave Unai Emery’s side the lead and a Kalidou Koulibaly own goal leaves the Gunners firm favourites to make the last four. “The first 90 minutes here we can impose a big plan,” said Emery. “They can control the ball with possession. They had one chance in the first half then two chances in the second half. We deserved a third goal. Away there is going to be different. We need to be focused and clear.”

Chelsea boss Maurizio Sarri was relieved to taste victory. “I knew it would be difficult,” said Sarri. “Our opponents are physical, but we were able to face that well and in the second half we played better. The second leg will be difficult as Slavia are dangerous away. Callum Hudson-Odoi had to rest but he is in my thoughts for the next match against Liverpool. The team showed it was able ‘to suffer’ and still end with a good result, which has not always been the case this season.”

Napoli host the Gunners in the second leg next Thursday with Chelsea and Slavia Prague resuming hostilities at Stamford Bridge on the same night. Impressive goalkeeper Alex Meret stopped the Gunners winning by more. Goalscorer Ramsey said: “To keep a clean sheet and score a couple of goals is a lovely way to start the first leg. We’re delighted with that. “We suffered a lot. They’re a good team and keep the ball well. We had to dig in.

“I should have scored again in the second half. We can go into the second leg with a little bit of a cushion, but we know it will be a difficult place to go. “They were unlucky not to go through (in the Champions League). They are a quality team. They’re a tough team to play against. We have given ourselves a great opportunity.”

Napoli coach Carlo Ancelotti is still confident his side can turn the tie around. “We didn’t start well,” he said. “The first half was not good and it was difficult to come back. “The result is difficult to change but we have 90 minutes again. We are totally confident (of turning the match around) with our supporters in our own stadium.” Meanwhile, Sarri’s under-strength Blues struggled to find rhythm for large spells, but grew into the game after Eden Hazard was introduced off the bench just before the hour mark.

Valencia won 3-1 at Villarreal — the winners of this tie face Arsenal or Napoli in the semi-finals — while Benfica overcame 10-man Eintracht Frankfurt 4-2 in Lisbon where teenager Joao Felix slotted in a brilliant hat-trick.