The weeks leading up to a historic Heineken Champions Cup semi-final isn't an ideal time for Leinster's normally-watertight defence, to start springing leaks.

Glasgow plundered five tries in last weekend's Guinness PRO14 tussle at the RDS while in the preceding league games, Benetton scored three and Edinburgh four.

In their European quarter-final, Ulster crossed twice at the Aviva Stadium and there could have been more.

"I was worried about conceding three tries in the last ten, fifteen minutes," said Blues senior coach Stuart Lancaster of the defeat to Glasgow, "But yeah, I'll continually worry about our defence when we play against Toulouse because they're such a good attacking team."

With talisman Johnny Sexton fit and available for selection and the likes of Robbie Henshaw and Devin Toner back in the mix, Leinster will be fully locked and loaded for the visit of Toulouse in Sunday's semi-final at the Aviva Stadium.

It's the French club's second visit to the capital this season and Lancaster points to their 29-13 win at the RDS in January as a reason to be unfearful.

"One of the things we did really well in the game at the RDS was, we defended excellently. We restricted Toulouse to very few line-breaks and obviously that one try at the end, they got when [Cheslin] Kolbe got away.

"It's such a big part of Leinster's game, that we get our defence right but also it's huge in beating Toulouse. You've got to be able to defend well."

Lancaster revealed today that out-half Sexton returned to full training at the end of last week, having missed the past five-weeks with a quad injury.

Should he play at the Aviva Stadium, it will be his first Leinster appearance of 2019.

Meanwhile, Tadhg Furlong is expected to be fit and was taken off in the defeat to Glasgow as a precaution.