Scotland: Sunderland striker Ross Stewart, Hearts defender Craig Halkett & St Johnstone keeper Zander Clark called up

Sunderland's Ross Stewart and Hearts' Craig Halkett have been called up by Scotland for the first time.

St Johnstone goalkeeper Zander Clark will also join the squad to replace the injured David Marshall.

Stewart has scored 22 goals in 38 games for the English League One side this season.

Halkett will cover central defence after Scott McKenna withdrew, with Liam Cooper and John Souttar sidelined.

Both first-time call ups could make their debut in the friendly with Poland on Thursday, with Scotland then playing either Austria or Wales the following Tuesday.

Meanwhile, captain Andy Robertson is a doubt after missing Liverpool's FA Cup quarter-final win against Nottingham Forest with illness.

Stewart played for Ayrshire junior clubs Ardeer Thistle and Kilwinning Rangers after several years in the pro youth system with St Mirren, Celtic and Partick Thistle.

He then earned a move back to the senior game with Albion Rovers and had stints with St Mirren and Alloa Athletic before coming to prominence with Ross County, where he scored 28 times in 82 appearances to earn a move south.

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Halkett has been a key member of the Hearts back three which has performed strongly to help the Tynecastle side to third in the Scottish Premiership.

Scotland are playing the Poles instead of their postponed World Cup play-off semi-final against Ukraine.

The game will be played at Hampden with £10 from each ticket sold going to Unicef's response in Ukraine following Russia's invasion of the country.

The Scottish FA