Marcos Alonso's late header helped Chelsea to a hard-fought 1-0 win away to Slavia Prague in their Europa League quarterfinal first leg on Thursday.

Chelsea boss Maurizio Sarri fielded a strong XI in Prague, including an in-form Eden Hazard, who was outstanding in a two-goal outing on Monday as the Blues beat West Ham to move into third place in the Premier League.

However, the visitors found chances hard to come by over the course of the first 45 minutes as the league leaders in the Czech top flight dug in with a raucous home crowd urging them on in a scoreless first half.

Despite a lack of goals, the second half provided some entertaining end-to-end football, with Slavia Prague's Ibrahima Traore stinging Kepa Arrizabalaga's palms from distance on 70 minutes and Chelsea seeing a goal ruled out for offside shortly after.

Alonso's header from an inswinging Willian cross as full-time approached wound up being the difference for Chelsea, who return home for the second leg on April 18 with an important away goal giving them the upper leg for passage to the semifinals.