The former striker believes his old side will beat West Bromwich Albion this week.
The duo are among the key players in the Gunners first team, with Welbeck in particular having returned from injury to impress this season.
Recent weeks have seen the Gunners struggling though, with draws against West Ham and Crystal Palace putting their top four place in danger.
The front line in particular has floundered, with the game against the Eagles in particular demonstrating their need for a world-class striker.
And Nicholas has criticised Welbeck and Sanchez for their displays, saying the latter in particular isn’t doing enough.
“I've actually got to the stage where I'm not comfortable watching my team,” he told Sky Sports.
“I'm not at the edge of my seat. It's so predictable and it's always Mesut Ozil that has to create. People criticise him because he's not quick and dynamic but that's not his job.”
“Danny Welbeck's movement is good but his touch and his finishing is poor and Alexis Sanchez still isn't doing enough.”
The former striker does however believe that his old side when they take on West Bromwich Albion this week.
The Gunners host Tony Pulis’ side at the Emirates in desperate need of three points as Manchester United chase them down in fifth.
And Nicholas believes they will get the win and it will be midfielder Mohamed Elneny, who has been a positive since joining in January, that will save them.
“Arsenal are in a really dangerous situation with United potentially just a point behind by this stage,” he added.
“I'll start on the edge of my seat and end the game hiding behind it, with another seriously uncomfortable night, and I think it could be Mohamed Elneny - one of the few impressive players - to save Arsenal.”