Former Barcelona, Liverpool and Chelsea midfielder Zenden was invited to join the Black Cats for training over the next fortnight and Bruce revealed he had already made a good impression.

The 33-year-old is a free agent after leaving Marseille at the end of last season, meaning he can be registered outside a transfer window.

Bruce told the Sunderland Echo: "I got a call from Bolo a little while ago and he said he was without a club so I invited him down to train.

"He's had a great career at some huge clubs and when an opportunity comes to look at someone with that background then you take it.

"He looks in very good nick, considering he has not had a club. He has been training in Holland and has obviously looked after himself very well."

Bruce accepts Sunderland are short of bodies in midfield after selling Dean Whitehead to Stoke and Grant Leadbitter and Carlos Edwards to Ipswich and allowing Teemu Tainio to join Birmingham on loan.

He added: "One thing that does concern me slightly is that we're a little light on numbers.

"Bolo has played at the highest level and can cover a few positions.

"He'll work with us for a couple of weeks and we'll take it from there. I dare say I'll sit down and talk with him after our next game.

"At the moment, there is no commitment on either side. He's having a look at us and we're having a look at him. But certainly his past record shows he has the calibre that you need in the Premier League."