United manager Jackie McNamara insisted this week that all the previous history between these sides is void, but it was only two months ago that he and opposite number Tommy Wright were both sent off for a touchline spat.
Wright was scathing about McNamara after that game, accusing him of taking cheap, disrespectful shots at the way his side were playing, and McNamara moved to douse any lingering embers prior to the final at Celtic Park.
"It's not about revenge, it's about winning silverware for this group of players," he said. "This is a cup final and everything that has happened in previous games goes out the window."
But McNamara, a three-time Scottish Cup winner as a player with Celtic, could also have done without being linked with the vacant manager's job at Blackpool this week.
He insisted it has been "no distraction for me at all", but wondering whether their gaffer will continue at the helm next season may well have been on the minds of his players.
But then football is rarely without distractions and the St Johnstone boss has had one of his own - that of the future of top goalscorer Stevie May, whose two strikes clinched his side's place in the final in a momentous come-from-behind victory against Aberdeen last month.
The club, whose only previous trophy is the 2007 Challenge Cup, are optimistic May will sign a new deal after the final and they were buoyed this week by fellow key players Steven MacLean and Lee Croft committing their futures to McDiarmid Park, while Dundee United's key midfielder Ryan Dow also signed a new deal at Tannadice.
But United need to assess defender John Souttar and winger Gary Mackay-Steven following recent illnesses. McNamara is optimistic of their involvement and has no other injury concerns.
St Johnstone, though, were rocked by a serious Achilles injury to Tim Clancy and he will miss the tie.
United beat Rangers at Ibrox in the semi-finals, proving they can handle such a big occasion. St Johnstone will take 15,000 of Perthshire's finest but they will still be outnumbered by almost two to one, with United having sold over 28,000 tickets.
St Johnstone, having finished mid-table in the SPL, are undoubtedly the underdogs but former defender Michael Duberry, remembered widely for his six-year spell at Chelsea, says that "will not bother them one little bit".
Watch Dundee United take on St Johnstone live from Celtic Park from 2.30pm this Saturday on Sky Sports 1HD.