Mulumbu has been in excellent form of late, but so too has Argentina international Yacob.
"It helps that I speak a little bit of Spanish and that's how we communicate," Mulumbu told the Birmingham Mail. "But Yacob is one player you do not need to speak to.
"He knows the role he can fill. He protects our defence really well and that gives me a little more freedom to play and go forward. In training we work really hard together.
"Every time I play I know where he's going to be - I know his position. It is easy for us to communicate because we feel the same way.
"The best thing with Yacob is that he never stops running. He offers me protection. For me it is unbelievable and how many balls he manages to win.
"When teams win quite often it is the striker who receives the praise.
"But when you see how far he runs, you'd be surprised - it's unbelievable."
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