Injury has kept the pair apart for large parts of this season.
But when they have played together, Xhaka has been encouraged by their potential as a midfield tandem.
"It is a shame we have not played a lot together, because he has had two big injuries. But the games we have played together, I think he looks very good, very solid," the Swiss midfielder said.
"We are very good together, not only on the pitch but off it as well. He is a lovely guy, he is improving our team because you can see how much experience he has at this level, and this is good for my game as well.
"As well, the other midfielders in the team are improving step by step and the important thing is that we can see and we can feel we are improving and we have to keep going like this and let's see what we can take from the end of the season."