The Glasgow Warriors fly-half Duncan Weir will make his first start for Scotland in Saturday's Six Nations championship match against Wales at Murrayfield after replacing Ruaridh Jackson in the squad announced on Tuesday. Weir, 21, who has won his three previous caps from the bench, is one of two changes to the starting line-up who defeated Ireland in the last round. The British and Irish Lions tight-head prop Euan Murray, who missed the Ireland match because he does not play on Sundays for religious reasons, replaces Geoff Cross who returns to the bench. "It's a moment I'll cherish and hopefully I can do the coaches justice for giving me the start," Weir said. The Scotland interim head coach Scott Johnson said Weir had played well after coming on as a replacement in the 12-8 win over Ireland on February 24. "He's a talent with a really good work ethic and a thirst to improve, which I like a lot," Johnson said. "Ruaridh remains a key part of our squad, but he knows with Tom Heathcote proving a match-winner for Bath and kicking goals from here, there and everywhere, that he needs to up his game too. "Geoff was a standout against Ireland and it's up to Euan, who fronted up big time against Italy, to raise the bar again." Scotland, who have beaten Italy and Ireland after losing to England in the first round, share second place in the standings with Wales on four points. England, the only unbeaten team, head the table with six points. The Wales prop Gethin Jenkins will miss the match after suffering a calf muscle injury during the 26-9 victory over Italy in Rome 10 days ago and is replaced by the Bath forward Paul James. Meanwhile, the Ireland fly-half Jonathan Sexton has been ruled out of his side's match against France on Saturday through injury leaving a place open for either Paddy Jackson or Ian Madigan. The coach Declan Kidney, who named the remainder of his team yesterday, will decide later this week whether to give Leinster's Madigan his debut or retain Ulster's Jackson who struggled with his place kicking in his debut against Scotland last time out. Sexton, bound for the French side Racing Metro next season, should be fit for Ireland's final outing against Italy along with the Ulster wing Gilroy, who will train later this week after suffering a groin injury, Kidney said. Follow us