2010 - Ospreys v Glasgow Warriors
To kick things off we turn the clock back six years to a semi-final between the Ospreys and Glasgow Warriors.
A number of major figures in the Ospreys' history were involved and in the second half it was inspirational playmaker James Hook who produced the game's defining moment.
With 53 minutes on the clock and the game delicately poised, Hook collected the ball out of the back of a ruck, skirted round the left, raced away down the blindside before chipping over the final defender and touching down.
That try set the Ospreys on their way to a 20-5 victory and they would go on to win the final away in Dublin a fortnight later.
2013 - Ulster v Scarlets
Back in 2013 the British & Irish Lions travelled to Australia, and just before the tour two of the Test wingers went up against one another.
Tommy Bowe of Ulster and George North of the Scarlets were the star attractions in Belfast, and it was the former who got the better of his opposite number on one memorable occasion.
With Ulster on the attack, the ball was switched back to the left where Bowe produced a fine sidestep to leave his future teammate clutching at thin air as he raced over for the try on the way to a 28-17 win.
2014 - Leinster v Ulster
On Friday night Ulster will travel to Dublin trying to do something unprecedented, but two years ago they came within eight minutes of managing it.
It was at that moment that Ian Madigan stepped up to score the crucial try that sent Leinster through.
Jimmy Gopperth delayed his pass beautifully and then Madigan's line allowed him to cut through in midfield, shake off another tackle and race over for the decisive score.
They would go on to beat Glasgow Warriors in the final, but if it hadn't been for Madigan they would never have had the chance.
2015 - Glasgow Warriors v Ulster
There was more heartbreak for Ulster a year later, as they went down in dramatic fashion away to Glasgow.
It was a moment of real class that proved decisive at Scotstoun, with Ulster defending a five-point lead heading into the last five minutes.
Glasgow poured forward desperate for a score, and Finn Russell's brilliant miss-pass put DTH van der Merwe in for the try that his fly-half also crucially converted.
Earlier in the game Stuart Hogg had played his part with a brilliant penalty from inside his own half. Given that Glasgow ended up winning 16-14, that score would prove crucial.
2015 - Munster v Ospreys
The second semi-final last year was another thriller that was decided in the very last minute of the game.
Simon Zebo's splendid try got Munster on their way, Ian Keatley starting things off before CJ Stander and Paddy Butler combined to send the winger over.
But there was everything to play for going into the dying stages, and trailing by three the Ospreys thought they had nicked the win when Josh Matavesi went over with time up.
Unfortunately for the Fijian centre, there had been a knock-on in the build-up and the try was ruled out, leaving the Ospreys to rue what might have been.
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