Hartson did not believe Rangers had the quality to see off Celtic.
Former Celtic striker John Hartson expressed his surprise at Rangers managing to win the crucial Scottish Cup semi-final against his old club.
Rangers won the match at Hampden Park on penalties, and it was the manner of the win which particularly caught the BBC pundit off guard.
Commenting on Twitter, Hartson expressed his surprise at the result, but admitted Rangers deserved credit for the victory.
I couldn't see Rangers beating Celtic today on penalties.Never thought they were capable. Nevertheless they have and must take credit.— John Hartson (@JohnHartson10) April 17, 2016
The game finished 1-1 after 90 minutes, with a goal apiece in a dramatic extra time making in 2-2 after 120 minutes had been played.
Rangers won 5-4 on penalties, with Tom Rogic missing the decisive spot kick.
The Gers battled fiercely throughout the contest, refusing to let Celtic's Premiership status and experience show, and the game has only served to whet the appetite for the clashes between the two teams next season, with Rangers recently clinching promotion back to the top flight.