Forshaw and Junior Firpo both went off injured, clutching the back of their left legs, in the space of two first half minutes at the London Stadium.
Marcelo Bielsa was forced to replace the senior pair with teenagers making their Premier League debuts in Lewis Bate and Leo Hjelde, but the Whites still managed to pick up a vital 3-2 win in the capital.
Speaking after the game Bielsa said the problems were muscular and the early double substitution was difficult to take.
“Of course, the game being so early on where we had constructed our best moments; to have to generate adaptation with two substitutions always has its cost,” said the head coach.
Firpo posted on his Instagram account after the game, saying: “Also, sad about the injury, I will work very hard to come back stronger.”
Forshaw has now followed suit, with more encouraging news for Whites supporters.
“Thanks for all the messages, it’s only a small hamstring injury,” he said.
“I’m fighting to be ready for Saturday, if not I’ll be back straight after the break.”
The former Brentford and Middlesbrough man spent almost two years out of action through a complex hip injury before returning to Bielsa’s side earlier this season and once again becoming a mainstay.

7. Toon look to raid Atalanta
Newcastle United have lodged a £42m bid to secure a double deal for Atalanta stars Duvan Zapata and Robin Gosens. (ANSA) (Photo by Emilio Andreoli/Getty Images) | Getty Images

8. Knight in demand
Leeds United and Newcastle United are both showing interest in signing Derby County midfielder Jason Knight this month. (The Times) (Photo by Ashley Allen/Getty Images) | Getty Images

9. Szalai wanted by Magpies and Hammers
Newcastle United are reportedly eyeing a move for Fenerbahce defender Attila Szalai. The Magpies are in a battle with West Ham United for the Hungary international. (Sky Sports) (Photo by Laszlo Szirtesi/Getty Images) | Getty Images


