Martinelli has started just five Premier League games so far this campaign and is yet to be included in a starting line-up during the club's European journey this season.
When pushed for an answer why, Keown responded: "Because the manager doesn't like him. It's as simple as that.
"I'm not there everyday, I'm not on the training ground. I thought it was very interesting Odegaard had gone internationally and said 'this is the best young player I've ever seen'.
"And he's from Real Madrid!
"So now it's time to let him fly. Let's look at the positives. Let's support him. When he came into the team I thought he did a great job. Not only was he making runs down the middle but he was coming back.
"He was like a Duracell battery.
"Keep him in the team. Play him. You've seen what you've done with Smith Rowe and Saka. Support him."
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