Return to Glasgow will tell us how much Leinster have kicked on since last season
Tonight's game in Glasgow could be a pretty good barometer of where Leinster are compared to last season.
Leinster certainly look like they're in a good place, sitting pretty at the top of their Champions Cup pool and second in their Pro14 conference, with eight wins from nine games in total.
When you're winning games but not yet at full tilt, it's a sign of a great team. But you need to be aware that there is room for improve-ment .
Last season, Leinster coasted through the PRO12 campaign, only to be found wanting in the semi-final against the Scarlets.
And now, having beaten Glasgow away from home in the Champions Cup two weeks ago - and backed up that result with a terrific win in Belfast - it would be understandable if there was a hint of complacency.
But that is one difference between youth and experience: youth will expect another win, while experience will expect a tougher game than before.
There's a lot of youth in this Leinster side, but plenty of experience too. If they can continue their form and win back to back in Glasgow, it would show that they have pushed on from last season. Nine wins from 10 would make for a great return from the first phase of the season.
They are in fine fettle. Last week's victory should not be underestimated, because I reckon Kingspan Park is the most daunting place for a Leinster team to travel in the PRO14.
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The old Celtic League has gone through some changes of late, in structure as well as in name. Yet the interprovincial fixtures are still sacred, still the bedrock and yardstick in this league. They remain vital for the game - and for the accountants.
For so long, playing Munster away was the toughest challenge.
That Thomond Park factor, Munster's 16th man, went way beyond the sideline roar.
It was meant to intimidate, provoke and irritate, and many teams fell apart in the face of it. But I don't think Leinster fear Thomond now.
As professionalism kicked into gear in the mid-1990s, playing at Ravenhill didn't seem that big a deal to us.
Ulster away was perhaps the least significant of the derbies. Not any more. Ulster have turned their Belfast home into something of a fortress, albeit their form on the road has been nowhere near as impressive.
Leinster's recent record there is not great, but last week they truly sacked the fortress. They were dominant, confident and composed.
As expected after their heavy European loss away to La Rochelle, Ulster came out of the blocks with all guns blazing, but didn't get much reward from a lot of ball and territory.
Leinster's patience in the first couple of minutes in this hostile environment is a credit to how far this squad has come.
There was a maturity about them as they soaked up a lot of pressure in those opening minutes with well-structured, committed defence.
Later, they capitalised on some erratic throwing by Ulster and Ireland captain Rory Best. There's a nice air of confidence growing in this team, with a splash of arrogance.
I liked the way they were clearly determined not going to get dominated by Ulster, and they controlled the game, as they had in the recent European matches.
There is a blend of youth and experience in the team that augurs well. Rob Kearney's return at full-back is timely ahead of the autumn internationals, and he provides vital extra leadership.
The fact they hardly broke stride when Noel Reid and James Ryan were forced off early on is no disrespect to the players themselves but a clear indication that this squad is growing.
It was great to see the forwards provide a platform for the likes of Jordan Larmour to excel.
Larmour caused Ulster all sorts of trouble when he came on and Leinster's use of him in the next few weeks will be very interesting, because he deserves immediate inclusion, alongside all those players he looked up to during his teens.