Black found a delightful way to win material here. What was it?

Solution:

When we came across this position in our usual search for stuff, we immediately recognized it. “Look, it’s that position!” The first time, years ago, we saw this position, it taught us a useful lesson about sacrificing knights on empty squares. This idea also involves a check and a discovered attack, so it gave us several ideas to add to our chess repertoire that we got to use in different positions over the years. We will never forget, though, this first lesson! This was from a game, O’Kelly-Ivkov where the latter played 1...Ne3+ 2.Kh1 [White wanted no part of 2.Qxe3 Rc2+ 3.Be2 Qxe3 4.Rxc2 f5 5.exf5 gxf5 6.Rc3 Qd2 7.Rc7 Rf7 8.gxf5 Qxb2 9.Rf2 Qxa3 and the queenside pawns are pushed through to victory] 2...Nxf1 3.Rxf1 and White decided to resign before Black could play his next move. It’s easy to see why: 3…b4 4.axb4 Qxb4 5.Rb1 Rfc8 and Black, the exchange up, totally dominates the queenside. At grandmaster levels this is called “hopeless.”

Send questions and comments to PTamburro@aol.com.