Charlton manager Phil Parkinson felt Scott Wagstaff's equaliser before half-time was crucial to his side's FA Cup victory at Luton.
Goals by Wagstaff, Joe Anyinsah and Johnnie Jackson earned the Addicks a lucrative tie at Tottenham in the third round as the Hatters were beaten 3-1 at Kenilworth Road.
Blue Square Bet Premier outfit Luton made a lively start and they came within inches of taking a deserved lead when Claude Gnapka's cut-back found Danny Crow, whose effort thudded off the crossbar.
But the hosts did go ahead when Kroca pounced from close range after Charlton goalkeeper Rob Elliott had kept out Crow's effort following an Andy Drury corner. Charlton were not to be denied though and came from behind to set up a clash with Harry Redknapp's side on Sunday January 9.
Parkinson said: "Our first half performance wasn't good - we were making bad decisions on the ball and we were second best. The goal we scored just before half-time was crucial and, in the second half, we put in a much improved performance.
"In the first half, I thought we were tense on the ball and that we needed to relax when we were in possession, maybe because we were looking at a trip to White Hart Lane and we forgot about putting in a performance. But in the second half we were very professional and we could've have claimed a couple more goals in the end."