The manager refused to blame the goalkeeper for Luton's goal in the first half, while he is confident the German striker will get back to his best
Frank Lampard defended Chelsea goalkeeper Kepa Arrizabalaga and striker Timo Werner following their 3-1 win against Luton on Sunday.
Tammy Abraham's hat-trick proved enough to win the FA Cup fourth round tie at Stamford Bridge, but the home side had their difficult moments throughout the game.
A shot from Jordan Clark squeezed past Kepa despite the goalkeeper getting a hand to to the ball as the visitors pulled a goal back at the half-hour mark, while Werner went on to miss a penalty late in the game.