Celtic had the final say in the last Old Firm derby of the season and as a result look assured of the Bank of Scotland Premier league title.

The Hoops, who triumphed at Ibrox thanks to first-half goals by Stilian Petrov and Craig Bellamy, now have a five-point lead with four games remaining for each club.

Celtic had dominated the first half and although Rangers had their moments, with the woodwork being hit and goalkeeper David Marshall making a number of saves before substitute Steven Thompson pulled one back in the 88th minute, the result accurately reflected the balance of power in Scottish football.

No Old Firm derby is without controversy and Rangers are set to face an inquiry into the incident in which Petrov appeared to have been hit by a drinks can as he foolishly celebrated his opener in front of Rangers fans behind the goal.

Celtic had already known that Rangers were vulnerable by the decision to bring Marvin Andrews back into the fray in place of Bob Malcolm. The centre back had not played for more than a month because of a cruciate ligament injury.

Celtic tore into Rangers from the off and had come close to scoring on a number of occasions before the home side had mustered a single decent opportunity.

Sotirios Kyrgiakos had needed to intervene in only the second minute to stop Bellamy capitalising on a slip by goalkeeper Ronald Waterreus and a run by the Welshman down the left that left Hamed Namouchi and Maurice Ross trailing had looked odds on to supply the opening goal.

In the end Chris Sutton somehow completely miskicked 10 yards in front of goal but the breakthrough was coming and was eventually supplied by Petrov in the 21st minute.

The Bulgarian leaped to head home a cross from the recalled Didier Agathe and his joy was clear.

It certainly was for the Rangers fans behind the goal as he deliberately taunted them and as team-mates came over a drinks can was thrown, hitting him on the head.

Referee Stuart Dougal, the official who had undergone a brain operation earlier in the season, blamed Petrov for inciting the fans and booked him.

Rangers had only a skied shot by the off-form Nacho Novo to show for their efforts until then but might have been on level terms had Kyrgiakos got more contact on a Fernando Ricksen free-kick into the six-yard box in the 34th minute.

Within seconds Celtic were 2-0 up, however, thanks to Bellamy's superb solo effort.

The Welshman accepted a pass from Alan Thompson and motored past his only challenger, Krygiakos, to cut inside from the left and plant a curling effort out of Waterreus' reach.

He too celebrated in front of the Rangers fans and he too was booked.

Rangers desperately needed a way back into the game and saw Ricksen blast over and Gregory Vignal wide.

Dado Prso left men in his wake before forcing Marshall into a fine tip-over and from the corner the luckless Andrews headed against the back post before the break. Namouchi, who had been preferred to Thomas Buffel, saw his follow-up effort effort blocked, with referee Dougal turning down appeals that an arm had been used.

Buffel replaced Ross at the break and Bellamy lasted just three minutes before being replaced by Craig Beattie, with objects apparently thrown at him as he departed.

The newcomer was denied by Waterreus from an acute angle in the box before Kyrgiakos was booked in the 54th minute for bringing down Petrov on the run.

Celtic were back on top and forced a procession of corners and there were more problems for Rangers when Michael Ball was hurt in a challenge with Agathe having given the ball away himself.

Andrews bravely blocked from Beattie and within seconds Marshall had to hack away at the other end to stop Buffel putting Novo through.

Chris Sutton did exactly that with Beattie in the 67th minute, however, and Andrews had no chance of catching him. Goal number three was on the cards but the striker, who had scored for the Scotland Future Team in Austria in midweek, panicked and fired hopelessly high before reaching the box.

Novo was denied twice in the space of a minute at the other end, first by a block by Marshall in the box and then by Jackie McNamara on the line after he had taken the ball round the goalkeeper from the next attack.

Waterreus made a save from a Stanislav Varga shot on the turn before Rangers replaced midfielder Vignal with striker Stevie Thompson with 14 minutes remaining.

The Scotland man's first contribution was to force Marshall into a fine tip-over and from the corner Agathe hacked a Kyrgiakos header off the line.

Andrews' agony was ended eight minutes from time when Malcolm came on and Thompson set up a frantic finale when he forced the ball home from close range at the back post following moments of pinball in the Celtic box.

Rangers threw men forward in search of an equaliser, with even goalkeeper Waterreus reaching the opposition box, but Celtic held firm to spark celebrations on the final whistle.

Teams

Rangers Waterreus, Ross (Buffel 45), Andrews (Malcolm 83), Kyrgiakos, Ball, Namouchi, Ricksen, Ferguson, Vignal (Thompson 76), Novo, Prso.

Subs Not Used: McGregor, Alex Rae, Burke, McCormack.

Booked: Vignal, Novo, Kyrgiakos.

Goals: Thompson 88.

Celtic Marshall, Agathe, Balde, Varga, McNamara, Petrov, Sutton, Lennon, Thompson, Bellamy (Beattie 48), Hartson, Beattie (Wallace 90).

Subs Not Used: Douglas, Henchoz, Lambert, Maloney, McGeady.

Booked: Petrov, Bellamy, Agathe, Hartson.

Goals: Petrov 21, Bellamy 34.

Att: 49,593

Ref: S Dougal (Scotland).