He was playing on the right side of midfield in the first half and was pushed slightly further upfield in a front three after the break.
Kai Havertz opened the scoring before a comical Ben Davies own goal saw the Blues run out 2-0 winners in the first leg semi-final of the Carabao Cup.
Tuchel has stated that Lukaku was always the club's number one choice during their pursuit of a striker last summer.
The manager also confirmed that the Belgian striker is in contention to return for the Blues in Wednesday's Carabao Cup game.
Chelsea and Liverpool played out a thrilling 2-2 draw in the Premier League fixture at Stamford Bridge on Sunday.
With Chelsea taking on Liverpool - two closest challengers to Manchester City for the league title - the match could prove decisive in which team stays in the hunt for the league t...
Lukaku gave an interview to Sky in Italy in which the Belgian said he was "not very happy with the situation" at Stamford Bridge.
Earlier this week, Chilwell underwent surgery on a knee injury and is expected to sit out the rest of the season as he works on his rehabilitation.
Chelsea will aim to keep pressure on Premier League leaders Manchester City and second placed Liverpool when they host Brighton & Hove Albion at Stamford Bridge on Wednesday.
Chelsea defeated Aston Villa 3-1 in the Premier League fixture on Sunday.