Marshall currently holds the position and made himself a national hero with his performance in Thursday’s play-off victory, including the winning penalty save from Aleksandar Mitrović which booked the squad’s passage to next summer’s tournament.
Gordon, however, is in strong contention as the first reserve after being preferred to Rangers’ back-up Jon McLaughlin for Sunday’s Nations League match in Trnava.
The 37-year-old, who made the move from Celtic back to Tynecastle this summer, insists he’ll be doing all he can to push the Derby County stopper for the gloves.
He told Sky Sports: "I’ll be playing as hard as I can, as well as I can throughout the season to try and make sure I’m in the squad. If my performances do that then I’ll be very happy.
"You never know what can happen in football. I just need to make sure I’m ready for any injuries or whatever. All I can do is focus on myself, stay in the squad and challenge for that position.
"It was massive [to be involved again]. It was the goal I set myself upon leaving Celtic, to get back in this squad. To play is obviously even better. I’m very happy to have been out there today. The result could have been better for the comeback but it was a good performance from the boys.
Steve Clarke’s men went down 1-0 in Slovakia. It was a highly frustrating 90 minutes from the visitors who were easily the better side but couldn’t find a way past Marek Rodak. It means Scotland will likely have to defeat Israel in their final game to clinch promotion to the top tier of the Nations League.
Gordon added: “We’re disappointed we’ve not got something from the game. It was our turn to rue the performance of a goalkeeper at the other end. There wasn’t an awful lot more we could have done, performance wise. We created a lot of chances away from home. It just wasn’t our day.
"We limited them to a few chances, which is got to be a positive to take into the next game.”