WITH half the game gone you would have bet the ranch on Glasgow taking their scoreline into the stratosphere - or, at the very least, matching the 54 points they had put past Zebre on the last two occasions the two sides met.

Instead, perhaps disrupted by emptying their bench so early, they struggled to get a foothold in the game in the second half and failed to score a single point. The sympathetic view might be that, with a bonus point already bagged, they relaxed a little, but the fact that two of their players - Glenn Bryce and Will Bordill - collected yellow cards in that period suggests they were not taking it all that easy.

Either way, the result, achieved in gruesome weather conditions, still moved Glasgow back to the top of the Guinness PRO12 table, and they are guaranteed to remain int he top two as the league goes into its three-week recess. They lost Peter Horne (concussion) and Sean Lamont (knee) at different stages, but the early indications were that neither problem was a great concern.

"Getting the job done in the first half was great as the weather then came in and it would have been hard, even if we played better to score tries in the second," said Warriors coach Gregor Townsend. "We played with pace, aggression and ambition and were clinical at times, but not so much in the second half."

Townsend had hinted on Thursday that Rob Harley's selection in the second row might be an audition for the same role at Twickenham next weekend, but that plan was scuppered when Adam Ashe felt a twinge in his neck - the injury that had kept him out for three months - and was withdrawn as a precaution. Harley was moved back to his customary blindside station, with James Eddie coming in at lock.

Niko Matawalu, who has been picked on the wing lately, was also back where the fans like to see him, playing at scrum-half, and he was busy form the start. Typically, his first contribution was a howler, a wild pass to nowhere across the Glasgow 22, but he atoned brilliantly soon afterwards with a trademark burst at the other end, slipping a pass to Rossouw de Klerk, who moved the ball on for DTH van der Merwe to collect his 40th try for the club.

Matawlu was not the only scrum-half to make a mark in the early stages, as Zebre nine Alberto Chillon left one on the rump of Kevin Bryce when he delivered a swift kick to the Warriors flanker at a ruck. Referee Ian Davies had no hesitation in reaching for the yellow card, and Chillon's punishment was increased a couple of minutes when Chris Fusaro spilled out of a driving maul to collect Glasgow's second try.

Zebre's defence at that stage was hardly worthy of the name, and it fell apart completely in the 27th minute when Matawalu again cut them open, figuring twice in a move that ended with Kevin Bryce barreling past two defenders for a try, his first in a Glasgow jersey. The only question at that point was whether the Warriors would have their bonus point before half-time, and the likelihood increased a little later when centre Matteo Pratichetti and flaker Mauro Bergamasco became the second and third Zebre players to be sent to the sin bin.

The fourth try was Van der Merwe's second. It came in the 36th minute, touched down in the left corner after a scrum on the right and efficient recycling against the 13-man Italians. The scuffle that followed was at the minor end of the spectrum, but it was probably the most fight Zebre had shown all evening.

With the rain teeming down and with Glasgow having all but certain of a full house of points, it was hardly surprising that the scoreboard fell quiet in the early stages of the second half. Glasgow also enjoyed the luxury of replacing all but one of their front five in those minutes after the restart, although Zebre robbed the crowd of one source of entertainment when they removed the 24st Moldavian lock Andrei Mahu, a man built like a brick toilet but lacking that item's outright pace.

Dion Berryman was no slouch, though. With the game seemingly settling into a trough, the New Zealander brought it back to life with a clever try for Zebre in the right corner, collecting a grubber kick sent through by full-back Giulio Toniolatti. The try arrived just before the hour mark and there was a clear impression at that stage that Glasgow had lost their rhythm and Zebre were starting to dominate.

Bordill and Glenn Bryce picked up their yellow cards in the final quarter, but Glasgow girded themselves towards the end and the Zebre revival was snuffed out. The Warrior's championship chase is very much on.

P Murchie (G Bryce, 62); L Jones, S Lamont, C Braid, DTH Van der Merwe; P Horne (R Vernon, 19), N Matawalu (A Price, 73); R Grant (A Allan, 40), K Bryce (D Hall, 48), R de Klerk (Z Fagerson, 40), J Eddie, A Kellock (captain; T Spinks, 46), R Harley, C Fusaro (W Bordill, 55), J Strauss.

T: Van der Merwe (2), Fusaro, Bryce

C: Horne (2), Braid

Zebre: G Toniolatti; D Berryman, Mirco Bergamasco (G Garcia, 64), M Pratichetti, D Odiete; E Padovani (L Orquera, 60), A Chillon (B Leonard, 40); A De Marchi (A Lovotti, 50), O Fabiani (L Leibson, 68), L Romano (L Redolfini, 420, Q Geldenhuys (R Giammarioli, 60), A Mahu (F Gerosa, 55), R Riccioli, Mauro Bergamasco (captain), V Berabo.

T: Berryman

Referee: I Davies (Wales)

Attendance: 5,528