The 27-year-old, who was on the Magpies’ radar during the January transfer window, has missed the last two games with a groin problem.
His absence from the backline has impacted Graham Potter’s side, with both matches ending in home defeats to Burnley (3-0) and Aston Villa (2-0).
It was hoped the former Bristol City man would return for the visit to St James’ Park on Saturday afternoon, however Potter admits that is looking less likely.
Potter said: “Adam Webster has had a little setback with his injury.
“We will see how he goes this week but looking unlikely for Newcastle.”
In Lewis Dunk’s absence, Webster formed a strong central defensive partnership with Dan Burn before his £13million move to Newcastle on deadline day.
Since Burn left the Amex Stadium for his boyhood club, Albion have conceded 10 goals in five games, whereas the Magpies have only shipped two.
Enock Mwepu and Jeremy Sarmiento - both out with hamstring injuries - are also set to miss out.
Meanwhile, Potter is hopeful Adam Lallana will overcome a “small” hamstring problem to play his part on Tyneside.
“Lallana felt his hamstring in the week,” Potter said. We will see how he goes for Newcastle. It was only a small one but enough to miss this game.”
Eddie Howe’s men, unbeaten in seven games, sit 14th in the Premier League table, four points above the relegation zone.