With the Rugby World Cup now less than a month away, time is in short supply for the key runners and riders as they bid to land in Japan in tip-top shape. The warm-up matches therefore become more crucial by the week and on Saturday a pair of old rivals – packed with Guinness PRO14 stars – are set to strut their stuff. With Italy, South Africa and Wales all resting, the onus is on Ireland and Scotland to carry the Guinness PRO14 international torch and you won’t want to miss a scrum, tackle or kick. Meanwhile, Leinster and Isuzu Southern Kings are also involved and the Celtic Cup is back. Rory’s exit parade continues There is a lot at stake for Ireland when they make the short hop across the Irish Sea to take on England at Twickenham. The last time these two sides met, in the 2019 Guinness Six Nations, England produced one of their best performances of the Eddie Jones era to leave Dublin with a handsome 32-20 win. Although Ireland have bigger fish to fry down the line, revenge will certainly be on their mind and head coach Joe Schmidt has picked a mean-looking side for the task. The match will also mean more to Rory Best than most. The Ulster hooker retires at the conclusion of the tournament and is set for his last appearance at Twickenham and – perhaps – his last against England entirely. To help him through, Best is flanked by two key pillars of the Irish pack in Leinster duo Cian Healy and Tadhg Furlong, with Munster’s Jean Kleyn, Peter O’Mahony and CJ Stander adding further bulk behind. However, it’s the half-backs which will dominate attention with Leinster’s Ross Byrne set for his first Ireland start at fly-half, while Munster’s Conor Murray at No.9 will guide him through. There is a further Leinster flavour in the midfield and back three – hardly surprising seeing as they are the current Guinness PRO14 champions – with Garry Ringrose, Jordan Larmour and Rob Kearney no doubt all eager to make an impression. Ireland on top of the world? Of course there is more on the line than just a World Cup warm-up match for Ireland, with the world number one ranking also up for grabs. Like a hot potato, it’s likely to change every week before the tournament begins in Japan and Wales – who reached the summit for the first time in their history last weekend – could be dethroned within seven days. All they require is to beat England, regardless of the score, and the title is theirs for at least a week. Townsend backs experience as Scotland look to get back on track North of the border, Gregor Townsend is hoping to wipe the slate clean after last weekend’s pulping in Paris as they welcome France to BT Murrayfield. Townsend has responded to that 32-3 loss by ringing the changes and the eye-catching move is to bring in Scarlets’ Blade Thomson for his debut at No.8. There is a strong Glaswegian vibe to this side, with five of the starting XV hailing from the second city while Edinburgh have two representatives. Despite it being Thomson’s debut, Townsend has opted for experience – bringing back the likes of Tommy Seymour, WP Nel and Ryan Wilson. Greig Laidlaw – a seven-year Edinburgh veteran and current Clermont maestro – grabs the No.9 jersey and the captaincy, where he will rely on a Guinness PRO14-heavy pack to deliver the goods. George Turner gets the nod at hooker, while Scott Cummings and Hamish Watson are also restored to the side. Four Edinburgh players – Simon Berghan, Grant Gilchrist, John Barclay and Blair Kinghorn – sit on the bench, alongside Glasgow’s Grant Stewart and George Horne. “We referenced a game in the changing room where we missed a performance against Wales a year ago and turned round in a week with a very good performance against France,” Townsend said. “The physical drive has to be right across the team. The players know that and know that is what should happen every time they play for Scotland.” Pre-season preparations Although the World Cup is on the horizon, the Guinness PRO14 is also hurtling into view – with the opening round of matches just over a month away. Interestingly, Leinster and Isuzu Southern Kings have taken full advantage of the international sides on offer and both are in action in the coming days. Leinster are set to face Canada in Ontario, while the Southern Kings head to Georgia for an intriguing warm-up clash. Celtic Cup returns If that’s not enough rugby for the weekend, then the Celtic Cup is also back – with four matches kicking off another season of action. Running across seven weeks, the tournament will see eight teams split into two conferences – a Welsh one and Irish one – with the top side in each progressing to the final on October 13. Leinster A are the defending champions following a 15-8 victory against Scarlets A last season and they start their defence at Cardiff Blues A on Saturday. Elsewhere, Connacht A face Dragons A, Munster A host Ospreys Development and Scarlets A host Ulster A.