You can't choose the piece for your opponent.
If he makes an illegal move, you can stop the clock and find the arbiter to complain. As long as it's a first offense I'd expect you just get some extra time on your clock.
If this happened to me I woudln't want my clock ticking down, so I'd pause the clock and tell him to go get a queen.
If I had a forced mate I woudln't ask him or anything, I'd just play it :)
I would stop the clock and call the arbiter, as he has made an illegal move. The arbiter should restore the position to the one before the b1 move, give you two minutes extra time on the clock, and tell your opponent he must promote the b pawn (since he had touched it). He should probably also remind him that if there is no queen available, he has the right to stop the clock and ask the arbiter for one.
Rules:
7.4.a If during a game it is found that an illegal move, including failing to meet the requirements of the promotion of a pawn or capturing the opponent’s king, has been completed, the position immediately before the irregularity shall be reinstated. [...]
7.4.b After the action taken under Article 7.4.a, for the first two illegal moves by a player the arbiter shall give two minutes extra time to his opponent in each instance; for a third illegal move by the same player, the arbiter shall declare the game lost by this player.
6.12.b A player may stop the clocks only in order to seek the arbiter’s assistance, for example when promotion has taken place and the piece required is not available.
All of this is assuming FIDE rules, and standard time controls. In blitz you could have claimed a win.
Also, if your opponent doesn't see a queen but instead puts an upside down rook on the square (as some do), it's great fun to say "j'adoube" and turn it the right way up :-)
Today I played a OTB game and my oponnent made an illegal move but I did not realise that he made an illegal move. Here is the game.
Here comes the continuation of the game after the illegal move :
i say you won the game and he can't get a redo
It is too late after he resigns.
Yes, you could notice it only later on and have the game reset to the position before that move (under FIDE rules). But then, maybe your opponent realized he made a mistake as well, uses the same tactic and resets the game when you are winning... it seems more sportsmanlike to just point it out right away, and it wastes less of everybody's time.
Hi chess friends
In my last OTB game my opponent played pawn to b1 , left the pawn on the board and pressed the clock.This is obvisously a rule violation,as he has to replace the pawn with a piece. Since I had mate in 3 moves and only 4 minutes left i did not cared about . I played my next move h8Q+ correctly by putting the queen at h8 and asked him what kind of piece is standing on b1. He said a queen but it was still a pawn. He argued that no queen was available, but as I asked him he found a queen which he placed at b1. In two moves I checkmated black by Qd8+ and Qd6 #. But if my h-pawn would be at h6 at he plays the b1 move incorrectly can I claim that he has to take a minor peace instead of a queen because he has made an impossible move b1pawn. In this case winning or losing depends on what piece is standing on b1. I am looking forward to your replies as international chess players. What are you thinking about this.How would you behave in such situations ?