The interprovincial rivals go head-to-head at Dublin’s Aviva Stadium on Saturday and a bumper crowd is set to be in attendance for what is a re-run of the 2012 final.

Leinster have been imperious this season and are yet to taste defeat as they look to avenge last year's Heineken Champions Cup final defeat to Stade Rochelais.

Ulster, meanwhile, are among the frontrunners in the United Rugby Championship (URC) and scraped through the Heineken Champions Cup pool stage thanks to a dramatic Round 4 win over Sale Sharks.

But Cullen warned that form can go out the window in all-Irish affairs: "There's certainly no guarantees, the favourites don't always win.

"That's the way it goes. It goes back to how you prepare during the week, the process of getting yourselves right and in the best possible shape.

"That's the exciting bit we need to look forward to, just enjoying that process of delivering day-to-day good habits, enjoying each other's company, pushing each other on, all that good stuff that you hear about.

"But we have a really good group there now and I think they'll work hard for each other, and that's what we'd love to see.

"There's so much can happen in this sequence of games, it's such an unusual sequence of games, different to what's been before, but it can all be over very quickly and you suddenly have a load of free weekends.

"So, it's making sure you take each week one-by-one, and we'll try do everything we possibly can to give ourselves the best chance in the Aviva.”

Cullen went on to underline how special an EPCR knockout stage game between two Irish sides will be, at a venue that will host the Heineken Champions Cup and EPCR Challenge Cup finals in May.

Leinster confirmed on Monday that over 48,000 tickets have been sold as the game looks set for a full-house.

"It's getting close to being a sell-out game, and I think it will be an amazing atmosphere and occasion for Irish rugby, because it's club rugby, provincial rugby, it's all that's good about the game here in many ways and that lays the platform for the international game really.

"Obviously for us the club game lays the platform for our game, so it will hopefully be a great showcase for Irish rugby."

Cullen harked back to the 2019 Heineken Champions Cup quarter-final between Leinster and Ulster as he reiterated how tense such affairs can be.

"We played Ulster previously in a quarter-final game, post-Six Nations as it was then as well, and it was an unbelievable nip and tuck kind of game,” he recalled.

“So there's two teams, in terms of selections they'll know each other very, very well. The derby games, there's the familiarity and all the rest.

"We'll put a plan together, see how everyone has come through Friday's game. There'll be some tight calls in the team but once the team gets named it's about making sure everyone is delivering for the team.

"We've a good group that's hungry and wants to be successful, put their own stamp on this competition, and it won't be easy but it's a great challenge."

Leinster Rugby head coach Leo Cullen expects his team’s meeting with Ulster Rugby in the Heineken Champions Cup Round of 16 to be an ‘amazing occasion’ for Irish rugby.