Source: https://www.andrewrobson.co.uk

Some bids in bridge are complete “sign off’s” – e.g. 1NT-2. Some are invitational – e.g. 1-3, and some force partner to speak again – e.g. 1-1. A few bids actually force partner to keep bidding until Game is reached; one such “Game-forcing” sequence is a jump rebid in a new suit by Opener – e.g. 1-1-2or 1-1-3.

Dealer South N/S Vul

9 7 5
A 7 5 3 2
Q 10
7 6 3
K 6
10 8
8 7 6
K J 9 5 4 2
Q 4 3 2
J 9 6 4
4 2
A Q 8
A J 10 8
K Q
A K J 9 5 3
10
West North East South
1
Pass 1 Pass 2
Pass 3 Pass 4
Pass 5 Pass Pass
Pass

South’s jump rebid of 2was game-forcing and showed at least five s and at least four s. North correctly gave “false preference” back to South’s first suit. South then bid 4to see if his partner could cooperate in a Slam venture. North – still unable to pass as game had not been reached – made the weakest bid by raising to 5.
West led 5 to East’s A and South trumped East’s Q continuation. He crossed to dummy’s 10, cashed Q and led5 to 2, J and West’s K. West returned K and South trumped, drew the last trump, led Q overtaking with dummy’s A, and led 9. East played 3, South 8 and West 6. 7 followed to 4 and South’s 10 won. The rest of his hand was high.

ANDREW’S TIP: A jump rebid in a new suit by Opener is forcing to Game.