I was part of Craig Brown's squads, although I hadn't really established myself at the time, when Jim Leighton and Andy Goram were going head-to-head and we are now in the same situation with Marshall and Allan McGregor.
That is testament to the improvement Marshall has achieved in his game because I wouldn't have said that a year ago.
He struggled for about five or six games when he went in there at first but another great performance against Poland in Warsaw in midweek means has now played the last three games without conceding.
McGregor hardly did badly but we will be in a better place to say for sure who is on top at the moment when Gordon Strachan names the team for the friendly with Nigeria at the end of May.
If Marshall starts against Nigeria then he will be starting in Germany when the Euro 2016 campaign gets under way. Gordon is too experienced and too shrewd a manager to play Marshall in four friendlies before our first qualifier and then throw McGregor in.
That is the good thing about the Scotland squad right now, there is competition all over the place. You have few chances to show the manager what you can do at that level, so those who have been in the team and have done a good job - and against decent opposition it has to be said, not the San Marinos and the Liechtensteins of this world - have a good chance of holding on to their places.
Up front, there is certainly competition and, for me, Steven Fletcher has it all to do to force his way back in. Again, things can change, and Steven Naismith could suddenly find himself out of the Everton team again and Fletcher could be back in for Sunderland, but I think we learned in midweek that we can't start Fletcher if he has not been playing regularly for his club. I know people will say we got away with it with Alan Hutton, who has gone on loan to Bolton now, but did OK for Scotland when wasn't getting a game at Aston Villa.
But you can't have too many players like that, especially in a forward role where you have to be sharp to create and take chances. Fletcher looked rusty while Naismith came on and looked the part.
They are different types of player. Fletcher drifts wide on to the flanks, while Naismith gives you a focal point. He makes things stick and uses his game intelligence. When we go to Germany, we will need a guy who works his socks off. I'm not saying Fletcher doesn't do that but you definitely know what you are getting from Naismith. Elsewhere, we have been crying out for a naturally left-sided full-back to gives us balance on that flank and while Andy Robertson did well from the bench I think the Germany match might just come a little bit too soon for him.
As for Scott Brown, there is no bigger fan of the Celtic captain than me. Every so often you have to take a flare-up with him; I'm not saying I condone it, but for me he has an all-round game. He has great vitality and energy, a technical player, who is confident, has will to win, strength of character and is a natural leader. I know Darren Fletcher has been captain but Brown is a real leader on the park and what weaknesses does he have? Not many.
The performance we produced on Wednesday night is exactly the sort of display we will have to come up with to get a result against Poland in the qualifying campaign.
When it comes to the group, you can take Gibraltar out of it, and take Georgia out of it - they might win a game or two but I can't see them sustaining it over a 10-match campaign - and that leaves four countries - Germany, Poland, the Republic of Ireland and Scotland - playing for three places, two of which are automatic, one a play-off.
I am naturally cautious but I am more positive than I have been in 10 years that we will qualify.