[Thranduil]

Deal: https://tinyurl.brid...se.com/4v26fr25

I doubled the 1♣ opener, planning to show a strong NT later. AFter both opps bid ♠ and my partner passed, I decided to pass too as defending seemed to be a much better chance than trying to declare anything opposite a dummy with most likely 0 points. But then my bot partner suddenly bids 3♦ with five small diamonds and one single point? That makes no sense. Of course I then bid 3NT, a doomed contract, thinking my partner might have a few points and opponents probably were light for their bids.

[P_Marlowe]

Hi,

3NT is garbage, 3D was a bid made in the protection seat.

The opponents told your p, that they have approx. 20/21 combined and a fit,
your T/O in the first round told your p, that he has a 8+ card fit in diamonds.
He bids 3D trying to push them 1 level higher, the bid is not inviting you to
join the party.

I am not saying I would have found the bid with 5332, but you are green.
The description is also a bit off, it states 3-8, but whatever:
You joined a party without getting invited.

With kind regards
Marlowe