This is the pivotal bid, where your show partner that you are unbalanced and tell them much more about your shape. Here are the seven common unbalanced hands starting with the most frequent: 5431, 5422, 6322, 6421, 6331, 5521, 4441. Let’s group them:
Group A contain the one-suiters. They have a six-card suit, which can be repeated. With 16+ pts, you should repeat the six-card suit with a jump bid.
Group B contains the two-suiters. They all have a five-card suit and a second suit of four (five) cards which can now be bid – almost certainly at the lowest level. If partner has responded in your four-card suit, great: support (with a jump, if holding extra values).
Group C, the 6421 (or the less frequent 6430) fit into both Groups A and B. You have a choice of rebid; you could repeat the six-card suit, or introduce the four. In general, you should choose the cheaper option.
Group D is the dreaded 4441 (but mercifully rare - under 3% of hands), the only unbalanced shape without a five-card suit or longer. Generally, rebid your cheapest four-card suit.
You open 1♥ and partner responds 1♠. What now with these unbalanced opening hands?:
|Hand a)||Hand b)||Hand c)|
♠ 2 2
♥ A Q 10 9 5 3
♦ A Q 2
♣ K Q
♠ Q 2
♥ A Q 8 5 2
♦ J 9 4 2
♣ A 2
♥ A J 7 4 3 2
♦ 9 2
♣ A Q 9 4