BRIDGE MASTERCLASS
ThE correct line here is to win the opening lead in hand with the king, and immediately play the ace of trumps. Then you cross to dummy with a diamond and lead a trump towards hand.
You will be richly rewarded for this play, when South holds the bare king, and the contract will still succeed when the trumps break 3-2 or North holds four to the king.
If trumps break worse than that, you will go down anyway, but you have given yourself the extra chance by cashing the ace first; your diamond losers will go away on the solid club suit.
This most common of safety plays is ignored by many players at Pairs, because they know they will get a poor score on the occasions when the king is ‘on-side’, as they have conceded an ‘unnecessary’ overtrick.