The former England midfielder smashed home a stunning winner to edge Boro to a fourth round victory over League Two Accrington, capping an impressive individual display on his return to the starting line-up for the first time since New Year’s Eve.
Downing has been linked with a move from the Riverside Stadium this month, but Karanka insisted: “I don’t know who was speaking. I have said Stewart was an important player for us at the start of the season. He is one of the few players who has Premier League experience.
“Once again, I showed that I trusted him and when I can give him a chance, I will.
“It wasn’t a coincidence because I told him at half-time that he was one of the best players on the pitch. He has not been playing and he went on to the pitch and showed he wants to play and is ready to play.
“Always when a player takes his chance, he is a player that you have to consider.”
It took Boro 69 minutes to find a way through the Accrington defence on a day when chances went begging.
But Downing was not found wanting when he took aim from 25 yards and drilled the ball past goalkeeper Marek Rodak and into the top corner to book a place in the hat for the fifth round draw, although Stanley midfielder Sean McConville wasted a glorious opportunity to level with seven minutes remaining.
Middlesbrough: Konstantopoulos, Friend (Fry 9), Bernardo, Gibson, Da Silva, Fischer (Traore 61), Clayton, Leadbitter, Downing, Bamford (Stuani 70), Gestede. Unused substitutes: Negredo, de Roon, Valdes, Forshaw.
Accrington Stanley: Rodak, Rodgers, Hughes, Beckles (Gornell 90), Donacien, Davies (Clark 74), Clare, Conneely, Boco (McCartan 74), Kee, McConville. Unused substitutes: Hewitt, Chapman, Edwards, Shaw.
Referee: A Taylor (Cheshire).