The Blues were outclassed from the off at the RDS and Isaac Boss, Nathan White, Dave Kearney, twice, and Leo Auva'a also went over for the hosts to wrap up a bonus point 52-9 victory.
But with a Heineken Cup clash with Bath now looming, Leinster boss Joe Schmidt is refusing to get carried away - although he was the first to admit Sexton now has a major rival at No.10.
"He's getting there," said Schmidt. "There is a big shadow cast by Jonny and it is good to see Ian coming out of that. There is a full spectrum to what he can deliver.
"He is a good defender, he directed the game pretty well and his passing game is really improving.
"He has got really good balance and is very quick to spot an opportunity and go for it and his kicking game is coming on.
"He still has lots to work on but I think Ian is making really good progress.
"We have to put that game in context because they were missing a lot of players.
"Penalties are always on my mind and one thing is for sure, we know we can't give opportunities to Stephen Donald or Ollie Barkley next weekend."
With Wales entertaining Australia on Saturday, the Blues were shorn of their star players including centre Jamie Roberts, full-back Leigh Halfpenny and international captain Sam Warburton.
"In the second half we just gave them to many easy opportunities," said Blues joint coach Justin Burnell. "And we didn't take ours and made it far too easy for them.
"It's frustrating because we're paid to do it week in week out and we came here with a half a team. We've got to prepare for the Heineken Cup now so there's just no let up."
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