ALEX McLeish is hoping United States-based players Sam Nicholson and Danny Wilson will be able to join his Scotland in Peru and Mexico after two more players withdrew from his squad yesterday.

Stuart Armstrong, the Celtic midfielder, and John Souttar, the Hearts centre half, are unable to travel to South and Central America due to hamstring and knee injuries respectively.

No fewer than six players have now pulled out of the original 24-man squad that McLeish named for the end-of-season friendlies eight days ago - Barry Douglas of Wolves, Ryan Fraser of Bournemouth, Allan McGregor of Rangers and Matt Ritchie of Newcastle United all withdrew last week.

McLeish has turned to former Hearts winger Nicholson, who moved from Minnesota United to their MLS rivals Colorado Rapids earlier this month, and ex-Rangers centre half Wilson, who joined Colorado in January.

The Scottish-based members of the travelling party leave Glasgow for London tonight and the entire squad will fly to Lima tomorrow.

McLeish has admitted that he will have to play two entirely different sides in the games in the National Stadium in Lima a week today and the Azteca Stadium in Mexico City the following Saturday due to the heat and humidity the matches will be played in.

The game in Mexico City will also be played at 7,400 feet above sea level and the altitude will also present problems.

"It is getting quite thin," said McLeish." We need to look for a couple of replacements. The guys going there will need to do giant killing acts in South America.

"Stuart has a little tweak in his hammy. He flagged it up right away after the game. He is not going to make it. He genuinely wanted to come. It is a shame to lose him – a very experienced guy with under 10 caps and a tremendous player.

"John has had to pull out. The kid is gagging to play for the full national team – he has come through the system and the process and had a good season.

"We have Johnny Russell – he will miss the first game but he will come and play in the second game. There’s a couple of other Scottish boys out there who have good experience we can maybe call upon.

"We have not made that fitness for duty call yet but that could be on cards. We will assess things in the morning."