If it was Munster who spoiled the Saints party last year, it was an Irish team containing Best that ruined Hartley's hopes of picking up a Grand Slam with England at the end of the Six Nations last month.
Now it is Ulster's turn to try to inflict more pain and anguish on the Saints hooker as the 1999 Heineken Cup winners travel to Milton Keynes for their first knock-oyt game in 12 years.
"I had a few words with Dylan after the international in Dublin an d I'm sure we'll carry on talking during the quarter-final on Sunday," said Best.
"He's a great player, not just in the tight but you see what he gets up to in the loose. He had a fantastic game against London Wasps recently and set up two tries.
"You want to test yourself against the best and there's no doubt he's one of the best hookers in the Six Nations - there's on doubt he's up there. He probably got a lot of unfair criticism over the last few years but at the end of the day he's still relatively young.
"A lot of it was just youthful exuberance, but he's got the captaincy now and is well settled down. He's a fantastic talent and he carries the leadership of the team on his shoulders very well."
While Hartley's side have returned to the form they showed in going through their Pool unbeaten with home wins over Wasps and Sale Sharks since the Six Nations, Best's Ulster team are second in the Magners League and riding on the crest of a six match winning streak.
"There is no doubt we are in a good place at the moment. Confidence has to be high after winning six games in a row," added Best.
"There were a lot of dark times at Ulster when we were struggling to win at home in Europe, let alone do anything away, and never mind threatening to get out of our group. But there is a core of players now who put a lot of faith in the set-up, especially when David Humphreys took charge.
"We've all signed contracts over the last two or three years with getting to this position in mind. Everyone had an opportunity to leave but, thankfully, we didn't and now it's bearing a little bit of fruit for the boys that did stay.
"Having said that, we're not happy with just a quarter-final, making up the numbers and then coming home to concentrate on the Magners League. We're very much there to try and win this quarter-final and there's no other place I'd rather be than playing in a quarter-final for Ulster."