Nf3 +

The Knight checks on f3. That move is "forced". Please come up with more challenging examples.

That move is certainly not forced.

Rb1?

OK Peter. Of course it's not forced, that's why I added quotation marks. What I was trying to get across is that there are hardly any (if any) attacking moves that make sense.

My idea is 1.. Rb1 2. Nxb1 Nf3+ 3 Rxf3 Rd1.

Well, beckett74, I think the idea of these puzzles is not to be able to spot a tactical idea, but to actally work the idea out (in your head) into the correct move order. Everybody sees that Nf3 is one idea. In this light, Nf3 is not the end of the solution, but a possible start. What's really challenging, is to find the exact winning line. We can al shout moves, can't we?

Thanks for saying what I meant to say, Arne.

i can't see how thomas's idea can be avoided , so i go with Rb1, Nxb1 AND THEN Nf3....

I stand corrected.