When You Don't Know What To Play

... Play the Queen's Gambit Declined!

At least, I think that's what the Russians used to say lol.

Another example of how harmonious the black position is in Lasker's variation of the QGD.  Everybody should have this as a 'solid' weapon.

Edit: It turns out my opponent was a Grandmaster, but with a FIDE rating of only 2392.