Teenage goalkeeper David Marshall strengthened his case to start at the Nou Camp on the same night that Robert Douglas remained on trial with UEFA.

Another impressive display by the 19-year-old rookie laid the foundations for Celtic's win at Dens Park - courtesy of Stilian Petrov and Henrik Larsson goals - which took them 19 points clear of Rangers at the top of the Bank of Scotland Premier League.

Marshall's performance would have given Martin O'Neill great encouragement as he will not know until Monday whether the Scotland number one has won his appeal against the controversial red card against Barcelona after UEFA put the decision on hold.

The Celtic manager has been looking at all possibilities - including recalling Magnus Hedman from his loan spell with Ancona - but the 19-year-old again produced a performance beyond his years to give the club encouragement for next week's UEFA Cup showdown.

Marshall was vital to the club's latest success, especially as his team-mates looked more than shaky in the first-half even with the return of Neil Lennon, Jackie McNamara, Alan Thompson, Didier Agathe, Neil Lennon and Larsson, who saved them against Motherwell.

Dundee had a glorious chance to go ahead after just seven minutes when they carved the Celtic defence wide open.

Garry Brady floated the ball over the top for Nacho Novo to control on his chest but with an erratic swing of his leg he totally missed it and Stanislav Varga intercepted.

Moments later and Marshall needed to be alert to race off his line to clear as Novo threatened to run onto Dave Mackay's long ball.

The Dundee attack continued to look menacing on the break and they soaked up the Celtic pressure comfortably in the early stages.

But the home side needed a great fingertip save from goalkeeper Julian Speroni to prevent the visitors scoring against the run of play.

Thompson exchanged passes with Larsson and he off-loaded instantly with a powerful left-foot drive which he turned around the post at full strength.

That prompted a change of gear and some slick passing from the Glasgow side, who again squandered a great chance to snatch the lead a minute later.

Larsson was surprised to find himself onside from Bobo Balde's long ball and instead of running towards the goal, he rushed his shot and fired straight at Speroni.

Speroni thwarted another Thompson curler, with a dive to his left, before the lively Novo fired low into the sidenetting after good work near the byline.

Mark Fotheringham, who scored a wonder goal with a similar position at the weekend, had a great chance to test Marshall when his side were awarded a free-kick in the 33rd minute after referee Willie Young had harshly penalised Didier Agathe for a foul on Novo.

The former Celtic boy strolled up and sent a right-foot curler towards the top corner of the net - but his former team-mate stretched and plucked the ball out of the air.

Marshall produced an even better save in the 38th minute, which turned the game, when he acrobatically turned Neil Barrett's 22-yard dipping strike over the crossbar.

That proved to be decisive as moments later Pearson nipped ahead of Fotheringham to win the ball before charging downfield on the counter-attack.

With just Larsson up, Petrov overlapped the young Scot and was picked out with the perfect pass before steering the ball past the hand of Speroni.

O'Neill made a change at the break with Varga failing to reappear from the dressing room to be replaced by John Kennedy which suggested more injury concern for O'Neill.

Both goalkeepers had a very quiet start to the second period but Marshall was scurrying across his goal on the hour to see Fotheringham's long-range effort past the post.

Dundee continued to push for the equaliser and Petrov needed to head Steven Robb's free-kick behind for a corner.

But Celtic increased their lead in the 68th minute when Kennedy nodded Petrov's free-kick into the path of the Swede and he slipped the ball past Speroni at the second attempt for his 30th goal of the season.

O'Neill could afford the luxury of taking off Larsson with 11 minutes to go and bring on Beattie.

Marshall again caught the eye by turning Novo's shot around the post in 90th minute but he was let down by his defence in the dying seconds as substitute Sebastian Kneissl pounced in the area to fire into the top corner from Robert Linn's ball.

However, despite the late loss of a clean sheet, the youngster's performance would not have gone unnoticed.

Teams

Dundee: Speroni, Mackay, Sancho, Mair, Hernandez Santos, Barrett (Cameron 79), Fotheringham, Brady, Robb (Linn 72), Novo, Milne (Kneissl 72).

Subs Not Used: Soutar, Jablonski.

Booked: Fotheringham, Barrett.

Goals: Novo 90.

Celtic: Marshall, McNamara, Balde, Varga (Kennedy 45), Agathe, Petrov, Lennon, Pearson, Thompson, Sylla (Smith 66), Larsson (Beattie 79).

Subs Not Used: Douglas, Lambert.

Goals: Petrov 38, Larsson 68.

Att: 8,593

Ref: W Young (Scotland).