Help with 5 month poodle house training

Our 5 month old miniature poodle pup is clean the majority of the time and goes outside or waits until walks to do his stuff. The one problem we have is when he is playing in the lounge with our older dog - they do the usual play fighting and mouthing one another. Suddenly in the middle of the game the pup will walk over to a corner of the lounge and pee. We have to watch him constantly and whisk him up as soon as he stops playing to go outside. He will do this even if he has been outside half an hour before they start to play yet he can hold on for up to 5 hours if in his crate.
We've tried ignoring it and we always praise him and reward him for going outside. Recently, when he has peed on the carpet, we have said 'no' very firmly and rushed him outside but nothing seems to work.
We're wondering if it's partly the scent clinging to the carpet fibres - although we clean the spot carefully and also hired one of those huge carpet washers to try to rid the place of any scent.
We don't want to keep him permanently in the kitchen but it's tempting!
Any advice would be welcome.
Thanks
Margaret

if he is only doing this when playing, he is simply forgetting. my 6mth old was clean in the house, until it came to playing, all the excitment just made him forget where he was. might be worth just calming him down after a few minutes and taking him outside, then resume play.

there is a product called urine off, i used it for cat pee, it worked instantly, might do the same for dogs.

Yes, many of the accidents we have at that age is when we have a visitor and they are having so much fun they don't notice they have to go until too late.

I am a strong advocate of watching the puppy, not the clock. No rule works in all cases. This is a case for deciding it has been long enough, and taking the puppy out.

Activity stimulates elimination. Vigorous play can mean the puppy needs to go out sooner than usual.

Hi Margaret welcome to Dogsey.

Although you seem to have pretty much house trained your puppy he is still very young . Dogs don't begin to get control of their bodily until four months of age and when they are excited or preoccupied with something, a puppy's immature bladder may be unable to cope and the puppy will have an accident.

If you are going to allow play sessions in the lounge I would make sure you puppy is empty when you do , in other words allow it when you know he has just been out and relieved himself.

Until your puppy a little more mature you may be better confined these games to the kitchen or garden

Regarding the urine stains on the carpet, even when cleaned the scent may remain prompting your puppy to soil there again. The stains need to be cleaned with a none ammonia based cleaner, white vinegar or biological washing powder are good for this purpose and shouldn't remove the colour from the carpet.

Thanks everyone for the really helpful and encouraging replies. We've noticed an improvement already.