Taking a chance

You open 1S and partner responds 1NT. What do you rebid?

South	West	North	East
1	Pass	1NT	Pass
?

South

 A K J 10 4

 8 3

 A 10 4

 A 7 2

2S? 2D? 2NT? None of them were greatly appealing to me with an unfamiliar online partner, so I jumped to 4S, hoping partner had a couple of spades.

She didn't, and diamond and spade finesses were both offside, but her long diamonds made good anyway, to the tune of one overtrick. Boldness rewarded!

The complete deal:

South	West	North	East
1	Pass	1NT	Pass
4	Pass	Pass	Pass

Lead:  4

North

 3

 J 7 2

 Q 9 8 5 3 2

 K Q 3

West

 Q 8 6

 A Q 10 4

 K J

 J 9 6 4

East

 9 7 5 2

 K 9 6 5

 7 6

 10 8 5

South

 A K J 10 4

 8 3

 A 10 4

 A 7 2