Sigurdsson left Tottenham for Swansea this summer and has made a scintillating start to life in Wales, registering assists galore.
But Monk says the Swansea midfielder holds no grudges towards Spurs and, in fact, 'really loved the club.'
"When I knew I had the chance to get Gylfi, and it was very likely, then I pushed for it. It was for the reason that he has contributed (this season) and I know that he can be effective," Monk told reporters.
"In terms of himself and Tottenham - I don't think there are any grudges towards them, speaking to him about his time there he had a fantastic time and he really loved the club.
"Yes he wanted to play more than he did, but he came back a better player and developed at Tottenham as a player.
"I think of course there will be motivation to maybe prove people wrong. That is always the way if you are let go from a club you want to go there and show them what you can do and hopefully we see that from Gylfi at the weekend."