Saints signed 27-year-old Stewart from Sunderland this summer when he was recovering from an injury he suffered last season with the Black Cats, showing big faith in him as a difference maker in the Championship.
Russell Martin handed Stewart his Saints debut off the bench against West Brom for the final few minutes of the match, where he replaced Armstrong.
Armstrong insisted that Stewart was very good when he came on and stressed that the forward is a remarkable character.
The Saints attacker also believes that the former Sunderland man is an excellent player and predicted he is going to be a quality asset for Southampton.
“He’s excellent”, Armstrong told the Daily Echo about Stewart.
“I know him from Sunderland, it’s been hard for him to watch the team because of his injury but what a character he is.
“I thought he was brilliant when he came on.
“You’ve seen how many goals he scored when he was at Sunderland.
“He is going to be quality for us.”
Now Armstrong will be looking to link up with Stewart in the upcoming matches to score goals and help his side to achieve promotion back to the Premier League next season.
