Janmaat played with Wijnaldum at Newcastle United.
He said, "The top three Premier League is not for me, but for Wijnaldum. At Liverpool, he immediately took another step forward, just as the entire team apparently has been able to do in recent years. I hope Wijnaldum wins the Champions League enormously."
Janmaat also played with Tottenham midfielder Moussa Sissoko.
He added: “I played back right and had Sissoko in front of me. How he raged against Ajax was really impressive. Sissoko is a good guy, but now Wijnaldum has to win."