Lukaku is a poacher inside the box. His finishing is good but he lacks pace. So some central defence with good awareness and experience will handle him quite well.
Not all striker needs pace, without his pace he still score good number of goal and that is what we will be seeing him do I'm Chelsea. Timo Werner just need to partner with him and Chelsea will become a strong title contender. Timo Werner has the pace so he can use that to trouble the defenders while lukaku get into scoring position to score.
Today we saw how good he is with link up plays, the second goal I think resulted from his dummy skills (by leaving the ball to pass under his leg) giving room for Mount to set up James for the goal. He also had other brilliant plays and it could have been more than one goal but he will just have to settle for one today.