Robbie Keane has turned down a request from his US club to miss the Republic of Ireland's Euro 2012 play-off second leg against Estonia on Tuesday.
Los Angeles Galaxy play in the MLS Cup final on Sunday and had hoped Keane might miss the Republic's game, given their 4-0 advantage from the first leg.
But Republic captain and record goalscorer Keane declined the request.
"The job is still not done yet. We have to be professional and do the job properly," said the striker.
"They requested me to come back with the final [against Houston Dynamo] on Sunday, but this could be one of the greatest moments in Irish history for me playing for my country.
"To miss a special night - hopefully - like this, it wouldn't feel right."
Keane insisted the Galaxy had understood his decision.
Richard Dunne says the Republic will not let up in the second leg against Estonia
"They requested it and they were happy with what the manager and the association said, so believe me, it's no problem," he said.
It is 10 years since the Republic of Ireland made it to a finals tournament, the 2002 World Cup in the Far East, and on that occasion, they also took the play-off route.
Then skipper Roy Keane, who had headed off on international duty nursing an ankle injury, was not present as their trip to the Far East was confirmed in Tehran having, to the surprise of many, returned to Manchester United following a 2-0 home win over Iran in the first leg.
The current captain said: "I don't want to get into what happened in the past,
"I can only speak for myself and what Ireland means to me, and you all know I turn up for every game.
"If I have got a slight injury, I still come in and try my best to play the game, that's just the way I have been brought up, that's the kind of player I am.
"I can only speak on behalf of me and for me, this is probably one of the proudest moments my footballing career, to lead this team to where we are now and to achieve what we have achieved."
