David Connolly launched a scathing attack on West Ham boss Glenn Roeder and threatened to walk out of the club after scoring on his debut.
Connolly was furious to have been left out of the starting line-up, describing the decision as "mind-boggling" following the 2-1 win at Preston.
And he claimed Roeder told him that Neil Mellor, who arrived on loan from Liverpool on Friday, was guaranteed a starting place - something denied by the Hammers boss.
"I had been part of the starting line-up in training all week, then we picked Neil up at a service station yesterday and I was told he would be playing instead of me," said Connolly.
"It was a mind-boggling, terrible decision, a real kick in the teeth. I was very disappointed with the manager and I told him so.
"You have to earn the right to play during training and in games, and I felt I had done that.
"It was unfair on Neil that he played, unfair on the team because they hadn't trained with him and unfair on me.
"I don't know if Neil is going to play all the time but if he is I am going to look for another club. I didn't come here to sit on the bench.
"I don't mind competition, but you have to earn the right to play. The impression I got was that Gerard Houllier only let Neil come because he was guaranteed to start.
"When Glenn told me I wasn't playing I was in total disbelief. How can he pick someone who has only trained with us for an hour?
"He could have signed for other clubs but didn't because he wasn't guaranteed a start. So why did he sign for West Ham? I can't believe it. I will speak to Glenn again about this. I have to."
Connolly, who joined from Wimbledon for £285,000 last month, replaced Mellor in the second half and quickly got on the scoresheet to give West Ham victory in their first match in Division One for a decade.
And Roeder tried to play down the rift with his new striker.
"I gave David his debut when I was at Watford," said Roeder. "He was an angry ant then, and nothing has changed.
"No one is guaranteed a first-team place at this club, so I don't know where he is coming from on this one. I am not disappointed - it is the world we live in.
"But let's get real. Ray Harford died today; look what happened to the boy at Watford, and then there's my own situation last year.
"It's nice to know he is going to speak to me, though. After all, he has just signed a three-year contract."
It was Roeder's first competitive game in charge since he collapsed after the home win over Middlesbrough in April with a brain tumour.