THERE is a lesson to be learned here. When you have changed your team as much as Glasgow Warriors coach Gregor Townsend did before sending his men out to face Zebre, it may be worth remembering that people are regularly cautioned to leave well alone and not mess about with what is working.

After yesterday’s Guinness PRO12 win in Italy, Townsend admitted he may have messed up when he started to make tactical replacements early in the second half, and he paid the price as he watched the rest of the match nervously, unable to do anything to change the momentum of the game as Zebre came back from 22 points behind to threaten an upset. If they had managed it, it would have been a travesty in the face of Glasgow’s handling and attacking flair when they had the original XV on the pitch, but it took magnificent defence to keep at bay the Italians, who have yet to win a match this season.

“We had to hang on a little bit with 10 minutes to go but the way we got the ball back and went through the phases was excellent and set up a chance to score with a penalty,” Townsend said.

“I look at myself first at decisions on when to kick at goal or take scrum or line-out. Decisions on when to put players on, maybe a bit too early. It definitely upset our flow. I felt we were in our rhythm so I will take most of the mistakes myself.

“We did not see much ball after that. When you are bringing on new players, a lot have not played for the team and you are taking off players like Fraser Brown who are playing really well. There is going to be a period of adjustment.

“I don’t know what the average age of the pack was at the end but it was pretty young. It was a great learning experience for them – they had to defend a lot of line-out drives, a lot of set-pieces, a lot of scrums on their own line. They put in a really good effort.”

With a weakened team out, it was always going to be tough even before the changes – last season they didn’t take the lead until well into the second half in the equivalent fixture – and it did not get any easier when hooker Corey Flynn pulled a hamstring in the warm-up and had to be replaced, resulting in a reshuffle among the forwards.

It was just the kind of disruption they could have done without and Things got worse when Glasgow stepped offside at the first ruck and SRU referee Lloyd Linton had no hesitation awarding the penalty, which Carlo Canna, the home fly-half, duly kicked.

When they had the ball, though, Glasgow were looking dangerous, with Nick Grigg at centre making early inroads. Lee Jones, on the wing, was held just short of the line, but Sean Lamont stepped up to take the offload and go over.

With inexperience an issue in many departments, the Scots were making too many mistakes to capitalise on their advantage and the game descended into an exchange of penalties. Rory Clegg landed two for Glasgow while Canna added another for the hosts.

A mistake that caused big problems followed, came straight from the kick-off in the second half with Glasgow losing the ball and allowing home wing Giovanbattista Venditti to rampage into their 22 before quick ruck ball handed hooker Oliviero Fabiani an easy levelling try.

Once again it was Grigg who made the running for Warriors, with a fantastic break from his own 22. Though he was tracked down by the defence and stopped short, the ball was quickly shifted across the field for Fraser Brown to shrug off some weak tackling as he juggled the ball and raced in for the third try to make sure his side had the lead at the break.

Grigg was at it again in the second half, laying on Lamont’s second try with a break through the middle and when Leonardo Sarto went over against his old club, it looked game over.

Zebre had different ideas, hitting back it the final quarter with Venditti and No 8 Andries van Schalwyk going over to bring the scores close.

However, Glasgow held their nerve and Clegg’s third penalty put daylight between the sides again, even though Canna rescued the losing bonus point after the 80 minutes was up.

Scorers: Zebre: Try: Fabiani, Venditti, van Schalwyck. Con: Canna. Pens: Canna (3) Glasgow Warriors: Tries: Lamont (2), Brown, Sarto. Cons: Clegg (3). Pens: Clegg (3)

Zebre: E Padovani; L Greeff (K Van Zyl, 52), G Bisegni (sin bin: 43-53), T Castello (T Boni, 52), G Venditti; C Canna, G Palazzani (M Violi, 56); A Lovotti (B Postiglioni, 64), O Fabiani (C Festuccia, 70), P Ceccarelli (D Chistolini, 62), J Furno (Q Geldenhuys, 47), G Biagi (C) (F Ruzza, 62), M Mbanda, J Meyer (sin bin: 34-44), A Van Schalkwyk.

Glasgow Warriors: P Murchie; S Lamont, N Grigg (S Hogg, 64), S Johnson, L Jones (L Sarto, 19); R Clegg, A Price (G Hart, 60), G Reid (D Sears-Duru, 52), F Brown (J Malcolm, 53), S Puafisi (Z Fagerson, 33-41, 53), R Harley, R McAlpine (C Hunter-Hill, 54), J Strauss, M Fagerson (sin bin: 34-44, L Wynne, 67), R Wilson (C).

Referee: L Linton (Scotland)

Attendance: 2,000