The controversial deal which should have seen Dean Windass move from Bradford to Middlesbrough will have to be renegotiated.

Windass last night completed the transfer, which was thought to involve Boro paying £600,000 up front, with a further £400,000 due at the end of the season should the Teessiders avoid relegation.

The two clubs are due to meet at Valley Parade on May 5, and while bottom-placed Bradford are almost certain to have been condemned to the drop by then, Boro could be fighting for their lives.

The two clubs fear such a controversial payment scheme could hit problems.

Other relegation threatened teams could raise question marks over Bradford's commitment to a game where they stand to benefit financially from a defeat.

''Middlesbrough have signed Dean Windass for a fee of up to £1m depending on performances,'' announced the club, although the transfer has not yet been registered with the Premier League.

''We have not received the transfer documents yet but we will be scrutinising them very carefully,'' admitted a Premier League spokesman.

Windass, whose contract will keep him on Teesside until the summer of 2003, vowed to prove his critics wrong again as he continued his fight against a return to the building sites.

The 31-year-old, who began his career at Hull after being spotted playing for local side North Ferriby and earning his living working on a building site, admits he has had his detractors over the years.

But he is relishing a fresh opportunity to prove that he can play at the highest level.

''Right through my career, I've had doubters saying that I'm not good enough,'' he said. ''I've proved everybody wrong and I'll prove them wrong again here.

''I'll work very hard and I love training. I've worked on a building site before and I don't want to go back to that."

Windass, who has been allowed to leave Valley Parade as part of a clear-out by Jim Jefferies in a bid to slash his wage bill for next season's expected Division One campaign, admits his decision to head for the North-East once Boro's interest was confirmed was an easy one.

''When my agent told me that the clubs had agreed a fee, I couldn't get here quick enough,'' he said. ''With the size of this club, they shouldn't be in this situation.

''I'm very positive that we'll stay up. It's every footballer's dream to play for a club like this.

''I'm really looking forward to it. Every game is difficult in this league with the situation Middlesbrough are in at the moment."

Manager Bryan Robson believes Windass can make a real difference during the crucial run-in.

''He's adaptable and can play up in the front line and score goals," said Robson.

''But also, when he's used as an attacking midfield player, he scores goals in that role as well.

''That's what we like about Dean - the versatility but also the goals side of his game. All you've got to do is look over the last nine games we've played - we're looking to get more goals.

''He's got a strong character, he enjoys his football, he works very hard for his team-mates and that's why we've brought him here.''

Robson admitted that there could be further arrivals before the March 22 transfer deadline, although he would not be drawn on the identities of his targets.

''We're monitoring a couple of players and I've made some initial inquiries, but there's nothing 100 per cent sure at the moment.

''But we're looking to add still before deadline. You just never know with the transfer system.

''Sometimes you feel you're getting somewhere with a club or with a player and then all of a sudden, they do a complete U-turn and you don't get the player you thought you were going to get.'