The Gunners caused mayhem going forward in Saturday evening's Premier League clash at Elland Road and Mikel Arteta's side led 3-0 at the break after a brace from Gabriel Martinelli was followed by a Bukayo Saka strike.
Leeds improved after the break and pulled a goal back in the 75th minute as Raphinha smashed home a penalty awarded for Ben White's foul on Joe Gelhardt but the Gunners added a fourth goal in the 86th minute through substitute Emile Smith Rowe.
Marcelo Bielsa' s Whites had ten players missing - eight of whom were injured - and defeat followed Tuesday night's 7-0 hammering at Manchester City and last weekend's 3-2 loss at Chelsea.
"It's a tough one to take again," said Forshaw, speaking to LUTV.
"We weren't great again in the first half unfortunately and we rallied at half time and I felt like we put a performance in second half.
"There was a slight sniff after the goal went in at 3-1 but the fourth goal was a sucker punch."
Asked why the first half was not great, Forshaw reasoned: "I'm not too sure.
"I think it's hard to analyse now. We will have to look back on the game and go from there but they have quality players in the final third and they punished us unfortunately."
Leeds had eight players injured for the clash - Kalvin Phillips, Patrick Bamford, Liam Cooper, Rodrigo, Pascal Struijk, Jamie Shackleton, Dan James and Charlie Cresswell all on the treatment table.
Junior Firpo also missed the Gunners clash due to suspension and Diego Llorente was an absentee, head coach Bielsa revealing the defender was ill and would miss at least the next ten days.
"Times are tough for us at the moment, there's no denying it," said Forshaw.
"Without making too many excuses we have got Covid cases this morning, we have got illness in the group, nine fit first team players unfortunately so we are stretched.
"We are counting on young lads and hopefully it will be good experience for them to help us in the future."
A message from the Editor:
Leeds has a fantastic story to tell - and the Yorkshire Evening Post has been rooted firmly at the heart of telling the stories of our city since 1890.
We believe in ourselves and hope you believe in us too. We need your support to help ensure we can continue to be at the heart of life in Leeds.
Subscribe to our website and enjoy unlimited access to local news and information online and on our app.
With a digital subscription, you can read more than 5 articles, see fewer ads, enjoy faster load times, and get access to exclusive newsletters and content.
Click here to subscribe.
For more details on our newspaper subscription offers click here.
Thank you Laura Collins