The Manchester United midfielder spent several months out of action as he recovered from a serious illness but has now won back a place in the Red Devils side under boss David Moyes.
In his international absence, Brown has been the stand-in Scotland skipper as Gordon Strachan's side have restored some national pride in recent times following the disastrous Craig Levein era.
Fletcher is poised to make his Dark Blues return in Warsaw next week and his midfield counterpart is more concerned with his impact on the field than who wears the armband against our Euro 2016 qualification rivals.
"It's not for me to decide," Brown said. "But it's great Darren is back, it's going to help us push for that second or third spot.
"It's huge. He plays for Manchester United, one of the biggest teams in the world.
"When he was fit he was playing week in, week out, so it shows what a quality player he is."
Wednesday's Warsaw clash gives Strachan an early chance to size up one of the teams who stand between us and a place at France 2016.
And Celtic star Brown reckons the race is wide open as a number of teams - including the Republic of Ireland and Georgia - bid for a finals berth in two years' time.
"We are an up-and-coming team," he said.
"We have played really well in the past six or seven games and if we can keep that spirit in the dressing room, we've got a great chance.
"It's going to be hard. Germany are favourites but the other three or four pushing for second and third place is going to help. The extra place will help as well.
"We have a good away record in the last few games as well so hopefully we can keep that going."