Out of contract in June, Johnstone’s performances for both club and country have led to a host of top-flight clubs sending scouts to watch him in recent months.
The England international had been expected to leave the Baggies last summer following a string of impressive displays in the Premier League. But with few top flight clubs in the market for a keeper at the time, a £6million bid from West Ham was the only offer Albion received.
Now established in the England set-up, Johnstone knows he needs to be playing Premier League football at the start of the 2021/22 season to have a realistic chance of going to the World Cup.
The 28-year-old has held talks with Albion about extending his contract at The Hawthorns.
But Premier League clubs are circling with the keeper potentially available on a free transfer this summer.
In a bid to jump ahead of the queue, Southampton are believed to weighing up a bid for Johnstone this January.
But according to reports, both West Ham and Tottenham are ready to offer him contract if he does become a free agent this summer.
Should Southampton bid, Albion will have to decide whether to cash in on a player they could lose for nothing in a few months time – or keep him to aide their push for the Premier League.
According to reports, Johnstone is settled with Albion and would prefer to wait until the end of his contract to decide on his next move.
Southampton, though, are believed to want a goalkeeper this January to rival Alex McCarthy for the number one jersey.
But Tottenham and West Ham are believed to be happy to wait until the end of the season – when their current number ones – Lukasz Fabianski and Hugo Lloris – are also out of contract.