Two minutes from the interval the Australian international pounced on a head-flick from Jan Vennegoor of Hesselink to drive home from close range.

In the 70th minute the big Dutchman secured the points when he headed an Aiden McGeady cross past Gretna goalkeeper Greg Fleming and Celtic substitute Georgios Samaras, on for McDonald, grabbed the third goal two minutes from the end.

Celtic have the chance to draw level on points with Rangers next week although the Ibrox side have a game in hand.

What is certain is that the game will be much more frantic than this match which saw Celtic run out easy winners after a poor first-half show by Gordon Strachan's side.

While Celtic retained the focus on catching Rangers, the aims of the SPL's bottom side were simply to see the season out, having received a hand-out from the SPL to pay wages and costs.

A clutch of Gretna fans unfurled a banner asking Sir Tom Hunter, the billionaire Scottish businessman and philanthropist, to help the club out of its current plight.

But it was the visitors who needed help in the first half to break down the determined Black and Whites.

The Borders side, with only Ben Wilkinson in attack, were pinned back from the first whistle but when Hoops' skipper Stephen McManus headed a Shunsuke Nakamura corner over the bar in the 10th minute, it was the visitors' first attempt on goal.

Celtic midfielder Scott Brown headed a cross from Gary Caldwell off his own shoulder from close range when he might have been expected to score seconds before a 20-yard drive from McGeady drew a good save from Fleming.

McGeady was the source of most of the Parkhead side's promptings but as the first half edged towards its conclusion still goalless, the Hoops' fans grew increasingly tetchy.

Nakamura's tame free-kick from 30 yards, which Fleming gathered easily, did little to lighten the mood.

In the 38th minute Robson turned on to his left foot 30 yards from goal and powered a shot in which Fleming was glad to simply punch away, the move coming to an end when Brown headed over the bar.

But two minutes from half-time the growing tension was alleviated when the visitors took the lead with a 'route one' goal.

Artur Boruc's long punt was flicked on by Vennegoor of Hesselink to McDonald, who gratefully volleyed low past Fleming from six yards out for his third goal against Gretna this season.

McDonald's goal should have taken the edge off the game but there was a scare for the Parkhead side three minutes into the second half when Gretna midfielder Brendan McGill, finding himself with space at the edge of the Celtic box when he received a pass from Ryan Baldacchino, drove just wide of the target.

A scrappy period ensued with both sides surrendering possession too easily - and neither goalkeeper seeing much action.

However, on the hour, Celtic survived more slack defending when McGill's cutback found Nicky Deverdics eight yards from goal but the Gretna midfielder missed the ball completely and Caldwell put the ball behind for a corner.

That escape spurred Celtic on. A minute later Vennegoor of Hesselink took a Brown pass, laid the ball off to McDonald at the edge of the box and his arrowed shot was parried clear by Fleming.

McDonald was then replaced by Samaras, who took a Nakamura pass before driving his angled shot from 20 yards past the far post.

In the 70th minute Vennegoor of Hesselink made sure of the points when he headed McGeady's pinpoint cross past Fleming from six yards out.

McGeady looked to get on to the scoresheet with an effort from distance but the ball flew high over the bar.

With two minutes remaining McGeady turned provider again when his cross was flicked home by Samaras but there was still time for Fleming to make a fine save from Vennegoor of Hesselink.