This is very open and scrappy with handling errors from both sides.

James Lowe nails a clearance and Leinster are deep in the Ulster half.

Dan Sheehan, Tadhg Furlong, Paddy McCarthy and Joe McCarthy are on, which is a very, very, very strong quartet to introduce off the bench.

That's superb from Ciaran Frawley, who leaps up to grab and up and under right at the posts.

He was under huge pressure there.

Off we go! Will Leinster respond?

Image source, Inpho

Tom Stewart absolutely sat down James Lowe for Ulster's third try.

He's a try-scoring machine. That was his 32nd for Ulster, and he's now only one away from breaking into the province's top 10!

Image source, Getty Images

British and Irish Lions legend Willie John McBride believes reverting to only using the bench to replace injured players would leave rugby as a "far better game".

Ulster hero Mike Gibson was Test rugby's first substitute when he took the place of Barry John for the Lions against South Africa in 1968.

Tactical replacements in the international game were not introduced until 1996, however.

In recent years, led by back-to-back World champions South Africa and their use of the so-called 'Bomb Squad', deployment of the bench is now considered an integral part of the game.

"We didn't have any reserves. If you got injured with Ireland, they put you on the wing because you knew the ball wasn't going to get there," McBride told the Ireland Rugby Social podcast.

"If you could stay on the field you stayed on and if not, you played with 14. So replacements were very important for injury."

McBride has little time for the modern-day approach to rugby as a squad game.

"I'll be quite honest, that's one of the things that annoys me terribly," he added.

"We have changed rugby from a 15-man game into a 23-man game and that drives me crazy. They talk about bomb squads...absolute nonsense.

"I think we should get back to a 15-man game with reserves for injury only and I think we'd have a much better game."

In their most recent Test match, a dominant 73-0 victory over Wales, South Africa named Cobus Reinach as their only back on the bench, bringing on seven forwards across the contest.

Chief amongst McBride's concerns is the fear that bringing on an almost a fresh pack during a game will increase the risk of injury.

"It's just not fair," he said. "The chances of injury are so much more because you've fresh men against tired men.

"These guys that they rush on at the end are 25 stone probably, huge guys who couldn't play 80 minutes of rugby.

"That's unfair for a start. The whole game is wrong the way they've done this."

Image source, BBC Sport

Image source, Getty Images

What a first half for Ulster!

After a long wait, Nathan Doak can only send the conversion wide.

Now, I'm not into rules admin, but surely that check could have happened after the conversion as Doak wasn't standing around and waiting for a couple of minutes?

It was tricky and out wide so I'm not saying he would have made it, but it all felt a bit unnecessary.

We've a break for the conversion as Jack Murphy was hit late and high by Charlie Tector earlier in the play.

Andrew Brace thinks it doesn't warrant any further action as the Ulster fly-half ducked just before contact.

Stuart McCloskey lives up to his Bangor Bulldozer nickname and barrels his way into the Leinster half, and wins the penalty advantage.

It's another poor kick from Sam Prendergast, who misses touch for the second time tonight.

Stockdale's clearing kick isn't perfect and he can only bring play just shy of halfway.

James Lowe almost gets away down the left as he fends off Baloucoune, but the Ulster wing does just enough to bring him down.

Leinster work it back inside and win a penalty as Ulster's disciple starts to slip.

Ulster are having a decent spell of possession but it's all around halfway.

Ulster's defence is incredible and they hold wave after wave of Leinster attacks out, but Jack Murphy strays offside and concedes the penalty.

Here come Leinster.

This is ominous as the forwards chip towards the line.

Leinster win the penalty advantage from the scrum and Ciaran Frawley races into the 22 after a wonder pass from Sam Prendergast.

He's brought down and play is brought back, but that was a real warning sign.

It's into the corner.

Robert Baloucoune hacks the ball into space and you'd be a brave man to bet against the Ulster wing in a foot race, but James Lowe does really well to read it and clear any danger.