With their World Cup seeding hopes resting on the outcome of their game against Canada on Saturday and Ireland's international against Argentina on the same day, Frank Hadden, the Scotland head coach, has been forced to make changes to the side that ran South Africa so agonisingly close last Saturday at Murrayfield.

Chris Paterson, Jason White and Thom Evans were injured in the 14-10 loss to the Springboks, a setback that means they have to beat Canada at Pittodrie and hope that the Pumas win in Dublin to be ranked in the top eight. The injured trio have been replaced by Simon Webster and Nikki Walker on the wings, as Rory Lamont drops to full back, while Alasdair Strokosch comes into the back row for White.

Simon Taylor, who missed Scotland's first two internationals of the autumn, is recalled at the expense of Allister Hogg at No8. “We've freshened up the side a little bit,” Hadden said. “We've kept the front five and midfield very much intact.”

If Ireland beat Argentina, then they will become one of four second seeds in the draw for the 2011 World Cup a week on Monday. Having delayed naming his side because of injury concerns, Declan Kidney, the head coach, named an extended 28-man squad as he waits for news on Paul O'Connell and Rory Best, who both suffered dead legs in the depressing loss to New Zealand last Saturday. Alan Quinlan faces the prospect of a disciplinary hearing after being cited for stamping against New Zealand, the outcome of which will affect Kidney's selection, which he will now reveal tomorrow. “The squad allows us to cover several combinations if anybody is ruled out of the game,” Kidney said.

Sébastien Chabal, who is contemplating a return home at the end of the season from Sale Sharks, has been recalled by France at lock for Saturday's international against Australia in Paris. Chabal takes over from Romain Millo-Chluski. Marc Lièvremont's other change is bringing in Sébastien Tillous-Borde, the Castres scrum half, for his fourth cap because Jean-Baptiste Élissalde, the first choice, has yet to recover from the effects of an illegal high tackle during last Saturday's 42-17 win over the Pacific Islanders. Napolioni Nalaga, the Fiji wing who was sent off for the offence, was suspended for 22 days yesterday by a disciplinary committee.

After beating England at Twickenham, Australia make three changes for the match at Stade de France, all in the forwards. Wycliff Palu and Dean Mumm come into the back row and Ben Alexander plays only his second match as a professional at loose-head prop.

To play Canada at Pittodrie on Saturday: R Lamont (Sale Sharks); S Webster (Edinburgh), B Cairns (Edinburgh), N De Luca (Edinburgh), N Walker (Ospreys); P Godman (Edinburgh), M Blair (Edinburgh, captain); A Jacobsen (Edinburgh), R Ford (Edinburgh), E Murray (Northampton), N Hines (Perpignan), J Hamilton (Edinburgh), A Strokosch (Gloucester), J Barclay (Glasgow), S Taylor (Stade Français). Replacements: D Hall (Glasgow), A Dickinson (Gloucester), M Mustchin (Edinburgh), S Gray (Northampton), R Lawson (Gloucester), D Parks (Glasgow), M Evans (Glasgow).