Loanees get cup green light.The game is expected to attract a capacity crowd of over 3,000, with the U's selling out their 1,000 allocation on Wednesday morning.
He returned as a goalscoring substitute against Shrewsbury and is fully fit ahead of the first round tie at the U's Essex neighbours.
Eastmond has been ever present since arriving a month ago, while Watt has missed just one game, the win at Orient following an injury.
"I'd like to thank Arsenal for giving us permission to play the pair of them, we're very appreciative of having players of their quality in our squad."
"It is great news that Sanchez and Craig, as well as Jabo, are available to us on Saturday, I'm delighted," he said.
Jabo Ibehre was already cleared to play and Dunne was pleased to secure the services of his other two loanees for the tie at Melbourne Park.
After discussions with Arsenal's management team, Joe Dunne has told the club's official website that the influential duo could face Chelmsford City.
U's loanees Craig Eastmond and Sanchez Watt are available for the FA Cup in the big Essex derby this weekend.