By Boluwatife Ezekiel Olaleye
The Spain international is on the verge of a return to Vicente Calderón after Chelsea agreed the sale of the forward to the Spanish La Liga giants.
Costa will now arrive back in Spain in January, but Koke insists the striker will not be able to simply walk back into the starting lineup.
“He knows there are great players in our team,” Koke told reporters.
“There is plenty of competition – he will have to earn a place, we are having a great season and it is good that Diego comes to make us better.
“I am always glad when an important player joins the group to help us to improve, and also because I had a special link with Diego.
“Every time I had the ball, I knew his next move, and he knew that I was going to give it to him, virtually every pass was a goal.”