Paul O'Connell tonight makes his first league appearance in Glasgow, and the significance of the last British & Irish Lions captain's presence cannot be overstated in terms of this RaboDirect Pro12 encounter.

Munster have not only lost their status as the pre-eminent Celtic force, but have lost it to bitter rivals Leinster. This meeting with Glasgow Warriors at Scotstoun will go a long way to indicating whether they might be able to reclaim it over the next few weeks.

Victory would give them a chance of a RaboDirect Pro12 play-off place, and help instil the belief that they can produce a major upset when they visit England's Harlequins in next week's Heineken Cup quarter-final.

Defeat would all but kill off those play-off hopes and, since he is one of a group of influential players who are together reaching a dangerous age, might even start to damage the aura that surrounds O'Connell, whose return for last week's potentially tricky derby meeting with Connacht helped galvanise a struggling side.

Naturally, the home team is wary of his involvement tonight.

"The difference he [O'Connell] made to Munster last week was evident," said Glasgow head coach Gregor Townsend.

"He scored a try just going round the corner, the driving lineout was very strong. He is a talisman for them . . . a fantastic player and, as an individual, he can control lineout and carries the ball well."

That this little piece of history is being made at Scotstoun is, though, also an indicator that Glasgow have earned respect by reaching the play-off semi-finals in two of the last three years.

Failure to do so again became unimaginable when they took over at the top of the table with only five games to go, particularly after their Scottish rivals Edinburgh did them a huge favour last week by beating their then closest challengers, Ulster.

Edinburgh are off to face Zebre in Parma tonight, embarking on a four-match run-in through which they hope to generate momentum for themselves.

While, then, Townsend believes there is still a chance of further help coming from elsewhere, as other teams in the bottom half of the table seek to salvage some pride, he acknowledged that Glasgow – they face other play-off contenders in their next three matches – must now look after things themselves if they are to properly challenge for the title.

"You never know how the games will go – there are teams out there who will want to finish the season on a high," he said.

"What we are expecting is for every team around us to win their games and we will have to win all of ours.

"Whether it is two, three or four games, we will have to take each one as an opportunity to win. If we are to be in the top two, I would imagine we have to win all our games."

They know, too, that they ought to be in an even stronger position to do so having established a 17-6 lead at Leinster last week before allowing the European champions to overhaul them in the closing stages and leapfrog them at the top of the table.

Townsend accepted that the way in which they had let that match slip was a missed opportunity.

"It was, and that was a term that we used going into the game and after the game. It was an opportunity missed to stay first and to close out the game when we were leading and in the end to score a try when we were on their line for a number of phases," he said.

The management have seized upon the renewed availability of a posse of internationalists to make sweeping changes to the side, to the extent that only six of last week's starting XV keep their places.

The most telling change is at stand-off, with Townsend reverting to Ruaridh Jackson, his preferred choice around the turn of the year and in the build-up to the RBS 6 Nations.

Jackson was, though, dropped to make way for his clubmate Duncan Weir during that international campaign, even after playing a part in Scotland's back-to-back wins over Italy and Ireland, in turn suggesting that the management teams at club and country may be prioritising different things.

"I thought Ruaridh played very well for us before going into the Scotland camp, and played really well in the Italy game, so he deserves an opportunity, he has not done anything wrong for us," Townsend said.

"There are a number of changes this week where there is not much between two players and the other one is getting his opportunity.

"We were a little bit off defensively last week, and in attack with our accuracy in passing, so that is reflected in the selection, as well."

Tactics also have been a consideration, apparently, Weir having played when Glasgow went to Munster and suffered their heaviest defeat of the season, a 31-3 hammering in December.

The way in which the two play-makers are being managed goes against long-accepted wisdom that for this position – more than any other – consistency of selection is vital in generating self-belief and consistent patterns of play and understanding.

However, as with all aspects of professional sport, the way that is being handled will be fully vindicated if the results are the right ones and Glasgow go on to win this competition, as resources and scheduling increasingly indicate that they should.