South is the dealer and with 13 high card points has enough to open. Without a balanced 15-17 HCP, he cannot open one notrump. He does not have a five card major so he needs to open his better minor. Since both his minors are three in length, South opens one club.
To raise a minor, North needs five cards but North has to show his four card majors first. He bids one heart, bidding his four-card suits up the line. South does not have a fit for North’s hearts and now bids his four-card major, spades. Not deterred by the size of the spades, South bids one spade. North seeing that they have a golden fit in spades and enough points for game (at least 25), bids four spades.
Note: In advanced bidding, North would jump to four diamonds not four spades. This is a bid called a splinter showing a singleton or void in diamonds with spade support. South with a minimum and four points in diamonds would sign off in four spades. Points opposite partner’s void or singleton tend to be wasted.
The contract: Four spades by South
The opening lead: The king of diamonds
South ruffs the opening lead keeping the ace as a stopper for later. South then tackles trump. Normally, with the ace and a queen, declarer would finesse for the king. Because he only has little spades, he cashes the ace first planning to play up to the queen. He is rewarded for this play as the king drops. He now stays away from trump.
South plays clubs, and West ruffs the third round and continues diamonds. Declarer ruffs in the dummy and plays a club, pitching a heart. West ruffs in again and continues diamonds. South wins the ace and plays a spade to the queen drawing the last trump and claims.
The result: Four spades making plus one for +650
Notes: Safety plays are important. With ace and queen empty opposite four small cards, there will always be one loser no matter what. So declarer loses nothing by protecting against a singleton king.
If declarer finesses the queen of trump, he will lose three trump and control of the trump suit. South wins the opening lead with the ace of diamonds and takes the spade finesse losing to the king. East returns a diamond, which is ruffed in dummy. South cashes the ace of spades and when he gets the bad news of the trump split, he ruffs another diamond and then runs clubs. West ruffs the third round of clubs and then plays hearts. South pitches a heart on a club and claims, making his contract.
The result: Four spades making for +620