Williams scored in Saturday's 3-0 win over Rochdale, as Pompey went fifth in the League One table.
There is little time to rest before Premier League giants Arsenal head to the south coast in the fifth round of the FA Cup on Monday night.
Williams said: “Everyone's focused on recovery because of the amount of matches we've got in such a short period of time.
“But of course we're excited and getting ready for what's a really big game. I'm an Arsenal fan, so it'll be a special one for me."