Fox got his chance after first-choice Scotland keeper Allan McGregor was ruled out through injury.
Strachan was Celtic manager when Fox was at Parkhead but the 26-year-old goalkeeper left the Glasgow giants in 2010 in the search for regular first-team football and arrived at Partick later that same year after brief spells at Queen of the South and Dundee.
"I take into consideration what Jim Stewart, the goalkeeping coach, says but in the games I have seen going to watch Partick Thistle live, he has made some big saves," Strachan said.
"He was one of the Celtic youngsters who wanted to go out and play. Scott went on loan to East Fife, he was desperate to play.
"His attitude has got him where he is today."
Scotland, who didn't qualify for next year's FIFA World Cup™ finals, host the United States, who have made it to Brazil 2014 at Glasgow's Hampden Park on 15 November before travelling to Norway for a match in Molde four days later.
Defenders: Christophe Berra (Ipswich Town/ENG), Gordon Greer (Brighton and Hove Albion/ENG), Grant Hanley (Blackburn Rovers/ENG), Alan Hutton (Aston Villa/ENG), Russell Martin (Norwich City/ENG), Charlie Mulgrew (Celtic), Lee Wallace (Rangers), Steven Whittaker (Norwich City/ENG)
Midfielders: Charlie Adam (Stoke City/ENG), Ikechi Anya(Watford/ENG), Barry Bannan (Crystal Palace/ENG), Scott Brown (Celtic), Craig Bryson (Derby County/ENG), Chris Burke (Birmingham City/ENG), James Forrest (Celtic), James Morrison (West Bromwich Albion/ENG), James McArthur (Wigan Athletic/ENG), Robert Snodgrass (Norwich City/ENG)
Forwards: Steven Fletcher (Sunderland/ENG), Steven Naismith (Everton/ENG), Matt Phillips (Queens Park Rangers/ENG), Jordan Rhodes (Blackburn Rovers/ENG)