Celtic are through to Friday's draw for the Champions League play-offs after beating Rosenborg 1-0 in Norway this evening.
The tie was in the balance after a 0-0 draw at Parkhead last week but Forrest sent a superb shot in off the bar midway through the second half to send Brendan Rodgers' side through.
Celtic are now guaranteed European football for the rest of the year, either in the group stage of the Champions League or Europa League.