Important! During a 'random-opponent' match, do not send the app to the background (or answer your iPhone), or you might lose the match and your J-coin stake.
Remarks about the translation
This is a warning inside an iPhone game, that warns the user not to send the application to the background (or in other words: switch to a different app) or answer any phone calls on their iphone during a "Random Opponent" match. Or else: they will lose the game, and their coin stake (bet).
A little contexr would be very helpful. Word "монет" represents what J-coins are, it can be omitted, if a user understands the concept of J-coins.