North could open 2NT with a balanced hand and 20 to 21 points, but his hand is not balanced and his hand is more valuable than that with a singleton ace.
He does not open a major because he does not have a five-card major. Therefore, he opens one of his better minor, diamonds. South has four or more spades and bids one spade. With spades as trump, North knows that they have more than the 25 points needed for four spades. Therefore, he jumps to four spades which gets passed out.
South wins the opening heart lead with the ace and takes the spade finesse which wins. He cashes the ace of spades and trumps are drawn.
Ruffing Finesse: Because declarer has a singleton diamond opposite the AQJ1098, he does not take the normal finesse because if it wins he cannot repeat it. He could ruff until the king falls, but the best way to play diamonds is to cash the ace and put the queen on the table. If the king covers the queen, ruff. Otherwise, if East ducks, pitch a club.
There is not enough trump in dummy to ruff three clubs and one heart, therefore it is best to draw trump and work with diamonds. The queen of diamonds wins and then East covers the jack. South ruffs and uses the setup diamonds to pitch all of his losers.
Result: South makes four spades plus three for +510.
-South could cash his side suit winners and try a cross-ruff. However, that is not the proper method with such a strong side suit like diamonds.
-Should South be in slam since seven spades makes? No, because two finesses worked and South only had a wasted jack opposite North’s singleton ace of clubs. It just worked out. One should not be in slam unless North splinters in clubs. That is an advanced topic for another column.
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