The 26-year-old has not played for Alan Archibald's side since the draw with Ross County in January as injury and the form of deputy Gallacher has kept him sitting on the sidelines.
Fox saw his fine form at the start of the Premiership season rewarded with a call-up to the Scotland squad, but now he has a fight on his hands to displace goalie guru Gallacher and return to the Thistle starting line-up after turning out for Scott McKenzie's Under-20 side against County on Monday afternoon.
Fox said: "It was good to get a game for the 20s and keep myself ticking over because it has been a frustrating few weeks for me.
"But that is football. Gall has come in and done well and kept his place in the team so it is up to me to win mine back.
"I missed the Killie game through injury and the gaffer has stuck with Gall since then, so I have to respect his decision and work hard to try and get myself back in the team.
"I think the two of us have worked well together and we are getting the best out of each other every day and, as long as the team does well, that is the main thing.
"It is hard to improve if you are not playing, you are judged in games and in training it is about staying fit and sharp.
"I am trying my best to push Gall and it is up to him to keep his form up, which he is doing just now. I just need to keep working hard and hopefully my chance will come again."
While it has proven to be a frustrating spell for Fox as he has found himself out of action, Thistle have hit a period of good form at just the right time as they bid to beat the drop.
Archibald's side have lost just two of their last 10 top-flight games and recorded their second consecutive home win with a 3-1 triumph over Hibs.
A trip to Inverness Caley Thistle is next on the agenda for the Jags as they attempt to put more distance between themselves and eleventh-placed St Mirren in the Premiership standings.
Fox said: "The gaffer made some great signings in January and the results have picked up in the last few weeks to go along with the performances, which have been good for most of the season.
"The boys are playing with a lot of confidence just now and we are confident we have what it takes to stay up.
"Our heads never went down during the winless run, but when you are winning games and picking up points, it does drive the team on.
"It has been really good recently and hopefully we can keep that going for the rest of the season and keep moving ourselves up the table."