And then there were two. Ulster entertain the Ospreys this Saturday at the Kingspan Stadium boasting one of the last two unbeaten records after four rounds of the Guinness Pro12, and with a new pep in their step after producing some sumptuous running rugby in their eye-catching win away to Glasgow last weekend. They really do play some lovely rugby.

While much of the focus has been on Joey Carbery's arrival on the Pro12 scene and Johnny Sexton's impressive return from injury last Friday when Leinster ended the Ospreys' unbeaten start, Paddy Jackson has not only continued where he left off in starting all three tests in South Africa, but seemingly added another dimension to his own running game.

The young outhalf came within a whisker of scoring what would have been a contender for the individual try of the season with some blinding footwork and a turn of pace from his own half, before finishing off probably the try of the Pro12 campaign so far.

Off turnover ball, Ruan Pienaar, Jackson and Cave moved the ball to Luois Ludik, ably filling in at outside centre. Ludik made the initial inroads when accelerating through and then linking with Pienaar on his inside, whose deft, fingertip transfer inside to Cave along with his well-timed pass inside to Jackson saw the outhalf finish from 30 metres. The first-half try which Cave finished off, having been initiated by Charles Piutau’s blinding footwork and pace on the opposite flank, was superbly finished off by the Ulster backline’s straight running and perfectly executed left to right passing.

“It shows the interchangeability of our backs, certainly from 12 out,” enthused assistant coach Allen Clarke of that Jackson try.

“The back three I thought were phenomenal on Friday evening. You compliment that with Cavey’s experience in the middle and Louis Ludik’s ability to move into the outside centre position, he had a huge role to play in setting that off. Jacko finished it fantastically. As a backline, Charles was on the wing and some people maybe wondered at that, but you saw how damaging he was to the opposition as well. That ability to play in a number of positions across the backfield was outstanding.”

Ulster appear to be hitting form at a timely juncture, as coming hot on the heels of their visit of the Ospreys they travel to Connacht and then Bordeaux in the Champions Cup, before hosting Exeter in the same competition and then Munster in the Pro12.

“The boys have been really good. They recognise that we’ve been good but we haven’t been brilliant. There’s a lot more to come from us. We had purple patches on Friday night. We probably didn’t convert that as we’d like to. It’s an area of the game as a team that we’re really trying to focus in on. You also recognise that this game is like all sport - it’s very dangerous to get ahead of yourself. It’s grounded on getting your job right, preparing well, training well and then performing well. If you do that consistently then more often than not, you’re going to come out the right end of the results.

“We’re playing a good side on Saturday. The Ospreys are loaded with internationals and Lions, and they’ll be coming here smarting after losing against Leinster. It’s a top-of-the-table clash. We’re top at the moment so we’re there to be shot down. It’s important that we maintain and improve upon our standards.”

Ulster's flexibility amongst their backs will be required again, with both Stuart McCloskey and Stuart Olding having pulled up with injuries (prior to Jackson's try), and each are ruled out of this Saturday's game. Clarke said of McCloskey: "The scan was only yesterday but he's going to be out for the short term, it'll be three-to-four weeks anyway. When it's clearer the facts will be released." But at least Olding's groin injury is not as bad as first feared.

“I think we were all relieved because we feared the worst, and he was smiling afterwards because of that,” admitted Clarke. “He settled but it’ll take a little bit of time, particularly with his feet and his ability to sidestep people. He certainly won’t be available this week.”

Against that, both Tommy Bowe and Andrew Trimble returned to training yesterday. "We'll see how they react to that. We've got a pretty decent squad for consideration on Saturday afternoon," said Clarke, in what will be one of the understatements of the season given their attacking riches in the outside three.

Craig Gilroy is also back this week, but against that their midfield options have been further depleted, with no prognosis yet on Luke Marshall's state of health after his latest reported concussion.

Working out what this Ospreys team are exactly about remains a bit of a puzzle, but their second-half comeback against Leinster showed their durability over 80 minutes.

To the Ulster backs thus far the glory, with the forwards nonetheless mindful of their key role in servicing them with quality ball.

“Like every team, you set your goals, short-term, mid-term and long-term,” said Clarke.

“As a forward unit, we’re fully aware of the quality that is from 9 to 15 and throughout the squad, and recognise what our responsibility is. The boys are really focused on getting their jobs right. It’s been pleasing. It’s only four games in. You’ve got to respect what they’ve delivered to date but we’re aware of the areas where we need to improve. The consistency of performance from the starting eight and the forwards who came on, I thought on Friday we delivered throughout the game. To a man, each position was covered.”

“It’s difficult to assess because they’ve played both the Italian teams at home,” admitted Clarke.

“Against Connacht, they had threats throughout the pitch. The game was tight for periods. The Ospreys have an ability to hit you from deep. They’re very good at converting pressure and field position into points. Possession, territory, accuracy, physicality are all going to come into play when you play against a team like the Ospreys, because they’re right up there in all of those.”