Nothing frustrates a coach more than seeing his side compound one error with another, so after a loss to Edinburgh last weekend that he described as "our worst performance of the season", Glasgow coach Gregor Townsend has challenged his team to get back to their old selves when they host Scarlets at Scotstoun tonight.

On the face of it, the Guinness PRO12 doctor could not have ordered a more restorative fixture for the Warriors than a clash with the men from west Wales. Townsend's side have not lost at home in the competition since November 2013 - when they went down 8-23 against Newport Gwent Dragons - while the Scarlets have not won on the road since February last year. Yet Townsend will have seen enough slackness in his side's display at BT Murrayfield a week ago to remind his players that victories do not just come as a matter of course.

A win this evening would move Glasgow back to the top of the PRO12 table, although form and league position suggests that Ospreys will overtake them again on Sunday with a solid home win against the Dragons. There is a long way to go before the Celtic/Italian competition reaches its conclusion, but the five-week break for European and international action after this weekend's round of games will be more comfortably borne by the Warriors if they know they are still firmly in contention.

Certainly, Glasgow cannot allow the disappointment of losing their grip on the 1872 Cup against Edinburgh to fester in their minds any longer than it has to. Sean Lamont, who comes back into the side in place of Sean Maitland tonight, has been around long enough to appreciate the importance of living for the next game rather than dwelling on the last.

"It's unfortunate we lost the Cup, but we need to move on from that," said Lamont, whose three Scotland appearances in November brought his cap count up to 91. "With tonight's game being our last Pro12 game for five weeks it does take on a lot of extra significance.

"If we want to target top four and a final place we need to get back on track against the Scarlets. We know that we weren't on point last week at Murrayfield and Edinburgh played very well. Whether it was a bit of complacency from us I don't know. But you can't be perfect all the time.

"Losing to Edinburgh and losing the 1872 Cup did hurt the boys. We need to park that side of it and move on, and the best way to do that is to win this weekend. That would also allow us to go into Europe on the back of a win and that is also very important for us."

While Scarlets' away record is execrable, Townsend made an interesting point with his observation about the way they tend to approach matches. "They tend to do well early in games," he explained. They score more points than other teams in the first 20 minutes.

"They get a lot of their backs onto ball and they are very aggressive in defence. We know we are up against a tough opponent."

While Lamont's return is the only change Townsend has made behind the scrum, he has performed more radical surgery on a pack that was a clear second best in too many areas against Edinburgh.

The scrum, which had held up well enough in two games against Toulouse, was a particular worry for Townsend. In that light, he has dropped props Gordon Reid and Jon Welsh from the starting lineup, bringing Jerry Yanuyanutawa and Mike Cusack in to take their places.

The return of Cusack, whose last appearance at Scotstound was more than two years ago, is particularly welcome. The 30-year-old tighthead has been kept out by a combination of illness and injury, but he has proved his worth in recent weeks with a handful of games for Currie and Townsend is confident that he can bring his legendary scrummaging presence to bear as he gets back into PRO12 action.

"I'm delighted that he's back and available and has fought his way through," said Townsend. "He has had a tough time, but he has not shown it. He has come into training and worked hard. He's a fantastic guy and everyone loves him at the club. Whether illness, injury or getting operations, he has stuck to his tasks."

John Barclay has been chosen in the Scarlets lineup, and a compelling performance on Scottish soil would do the former Glasgow flanker's prospects of an international comeback no harm at all. Scarlets, who notched a surprise win against Ospreys last weekend, have also included fly-half Rhys Priestland, whose controversial move to Bath was confirmed three days ago.