Slavia Prague star Miroslav Stoch cannot wait to try and knock out his former team.
Stoch was at the Blues from 2006 to 2010, even though he was on the periphery of the first team.
Now the flying winger is hoping to make an impact for his club as they face Chelsea in the Europa League quarter finals.
"They got in touch when I was about 15, and I went there for a few trials, then I transferred when I was 16," Stoch said to Goal.com.
"It was a huge step for me, a whole different world. I couldn't say a word in English, so the first three or four months were tough for me.
"They put me, along with two Finnish and one Swiss player, into an English family who helped us to fit in. Once I started to talk, it was all good. I eventually made it to the first team. My team-mates are all huge legends. I am honoured that we shared the same dressing room.
"It was the best experience. To learn as a young player from the very best is a great opportunity for every young player and I am grateful for that. I always wished to draw Chelsea [in the Europa League], not just because I played there, but because I have been a Chelsea fan since I was a kid.
"We are enjoying the fact that we made it to the quarter-finals. To play against an English team is a dream for everyone who hasn't played against them before.
"Chelsea is such a great opponent that it feels like a Champions League match. We see it as a reward that we will play against a club like Chelsea. We beat another team that has won the Europa League [Sevilla]. Why were Slavia so successful over two legs despite being considered underdogs?
"They [Chelsea] have top players, in some positions maybe even the best in the world. But, of course, they would probably imagine having better results in the Premier League. Of course [Chelsea are favourites], but we aren't giving in.
"Everyone knows that the biggest stars of Chelsea are Eden Hazard and N'Golo Kante, I am looking forward to playing against them. I believe that, if we prepare well, choose the right strategy and play the same way that we did against Sevilla – together as a team and put our hearts into it - then we can succeed, even against Chelsea."
