Squeeze

From actual play, Jan. 7, 2009. Play this hand. (I am not sure there is one right answer.)
                 J85
                 A1098
                 Q8
                 K652

                 AQ
                 K3
                 AK32
                 AQ1094
You are in 6NT on an uninformative auction. The opening lead is the 4 of diamonds. Matchpoints, so you would like an overtrick; your opponents defend well.

You win the opening diamond lead in dummy and cash five clubs. Righty throws a spade, the nine of diamonds, and another spade. Lefty throws two spades and then, after some thought, the 6 of diamonds.

Now what?

Answer