Kovacic was on the bench at Everton on opening day but has been struggling with an ongoing knee issue throughout the summer which will see him miss this afternoon’s high-profile capital clash.
Alonso, meanwhile, is also ruled out due to an imminent transfer to Barcelona that has seen him training alone at Cobham.
“[Alonso] is not in training at the moment and trying to finalise his transfer so he will not be available for the game,” Chelsea boss Thomas Tuchel said on Friday. “It’s the same for Kova, who is injured.
"He has issues with his knee, always a little bit of a reaction. We decided to take a step back and increase treatment time to reduce the stress that comes from training to have a normal reaction before we start again. Everybody else is available.”
Chelsea have switched things up after winning 1-0 at Goodison Park last Saturday thanks to Jorginho’s late first-half penalty.
Ben Chilwell’s fitness amid his ongoing recovery from a major knee injury leads to him dropping to the bench.
Marc Cucurella comes in for his first start and home debut in west London. Raheem Sterling and Kalidou Koulibaly will both make their home debuts against Tottenham.
Ruben Loftus-Cheek is preferred at wing-back, with Reece James moved into central defence.
Chelsea XI: Mendy; James, Thiago Silva, Koulibaly; Loftus-Cheek, Kante, Jorginho, Cucurella; Mount, Havertz, Sterling.
Subs: Kepa, Chalobah, Chilwell, Azpilicueta, Gallagher, Ziyech, Pulisic, Hudson-Odoi, Broja.