'They are lethal' - Costello warns Munster ahead of Saints match

And Costello has warned his players that this weekend's opposition will be 'a whole different threat' to the Saracens side they beat at Thomond Park last Saturday.

Munster showed their grit as they defeated Mark McCall's men 17-12, coming back from 9-3 down to pick up the crucial Investec Champions Cup pool stage win.

Saints lost 45-35 at Stade Français on the same day and although the try bonus point they picked up made sure Phil Dowson's men have qualified for the round of 16, they will be eager to see off Munster and book a home tie.

Costello is well aware of the threat the black, green and gold will pose at a sold-out cinch Stadium at Franklin's Gardens this Saturday (kick-off 3.15pm).

And he will turn to Chris Boyd for advice, with the former Saints boss now a performance consultant at Munster.

“Northampton is a whole different threat altogether,” Costello warned.

“They have unbelievable speed, probably the best passing team that I’ve seen, and they’re just starting to hit a bit of form.

"We have had some good battles over there.

"We will take a lot of confidence from keeping Saracens try-less, but we have to be realistic and know that it is a whole different threat.

"(Former Saints boss) Chris Boyd is here to give us a few tips as well.”

Costello was delighted with the character Munster showed last weekend as their strong bench helped to propel them past Saracens.

“Our prep has been building really nicely and I can’t say enough about how hard, and I’ve said it repeatedly and it’s probably sounded hollow, in our building it has been, very different," Costello said.

"We’ve been prepping really well, there’s been real tightness, real connection and alignment and the character, fight and work-rate stuff has been there as a really solid foundation and there was a bit more accuracy.

“We have to carry that into Northampton. They are lethal. They can score anywhere at any time and they can change a scoreboard so quickly.

"We have to make sure that our next seven days are on point, we have to arrive again with the right mindset and be really fresh to give ourselves a chance of topping the group.

“I don’t think it will be 6-3 at Northampton. I don’t think there will be a lack of tries, so the team that wins will have to score a few tries as well.”

Munster are now second in Pool 3, level on points with Saracens and only a point behind Saints.

While Saints and Munster square up on Saturday, Saracens host Castres, who are just two points behind pool leaders Saints, on Sunday.

“I suppose it puts it in our hands to a certain degree,” Costello said.

“We’ve got to assume Saracens will get five (points), I think that would be likely for their last game at home.

"So we’ve got to, first of all, go and try and win the game at Northampton and then there’s a good chance that gives us a home round-of-16 (game), or it will.

"If we top the group, the seeding can be important as well."