Leading Against A Slam by Matthias Huberschwiller

A: ♠9 - Against a No-Trump slam, you need to lead as passively as possible, so as to not risk giving away a trick on lead. Therefore, a Heart lead is impossible.

The safest lead is a top Spade.

Your result so far:

A: ♣J - You might have read somewhere that against a suit contract slam, you need to make aggressive leads, to set up a trick quickly. That would indicate a Spade lead here.

That is partially true, and especially when they have bid other suits, on which they can discard their losers. That's not the case here, though. Lead a passive Club, hoping declarer will take (and lose) finesses in both major suits.

Your result so far:

A: ♦2 - Look at the bidding sequence. Why did they stop in 4♥?

They don't have a Diamond control. Therefore, your partner must have the ♦A. Lead a Diamond, to cash as many of them as you can before declarer can discard them.

Your result so far:

A: ♦2 - Here, you need to make an aggressive lead, to try and set up a Diamond trick while you still have the ♣A as an entry.

Your result so far:

A: ♦A - Cash your Ace quickly, then wait to make your natural trump trick.

Your result so far: