Bradford assistant Steve Parkin says Nahki Wells is not for sale after the striker scored in his side's 2-0 win over Sheffield United.
Wells scored both goals in a highly-charged Yorkshire derby, taking his tally for the season to six breaking a club record.
The Bermuda international broke the record when he put Bradford in front a minute before half-time with his eighth goal in consecutive matches - five this season and three in the final three matches of last season.
He collected a headed pass from Garry Thompson and turned the ball past defender Neil Collins before scoring with a low shot into the far corner.
Wells then put the result beyond doubt with Bradford's second goal thee minutes from the end, turning the ball into the net from fellow striker James Hanson's pass after goalkeeper George Long had made a superb save to deny substitute Raffaele De Vita.
Parkin said: "As far as we are concerned he is not leaving Bradford City.
"Other clubs have had 12 months to have a look at him and we are not going to sell him a week before the transfer window closes.
"Both chairmen let us put a squad together to get promoted last season and hopefully to get promoted this season.
"You don't sell your best players if you want success. It is a no-go area.
"It is terrific when you have a goal scorer like Nahki in the team, but he has a long way to go and it is important that he keeps his feet on the ground and keeps learning from the manager and the staff."
Both sides had other chances as play swung from end to end, keeping a bumper 18,042 crowd entertained, but Wells' finishing proved the difference.
United's best first-half chance came after only two minutes when Scot Jamie Murphy outpaced the Bradford defence after running on to a pass from Lyle Taylor, but Jon McLaughlin saved the shot with his legs.
The visitors piled on the pressure in the second half when they forced five corners in a sustained 20-minute spell, the most dangerous moment coming in the 64th minute when substitute Ryan Flynn's 20-yard shot rebounded off Thompson, but McLaughlin turned the ball over the crossbar.
Parkin added: "There was some great defending from our players when Sheffield United had that good spell and to come back at the end and get that second goal was fantastic."