Rashford scored the only goal on Sunday as Manchester United beat Tottenham 1-0 at Wembley.
The striker latched onto a delightful pass from Paul Pogba, raced away from Jan Vertonghen and finished inside the far post past Hugo Lloris.
It was the first time Rashford has scored in three consecutive Premier League games in his career.
Rashford has started all five of Ole Gunnar Solskjaer’s Premier League matches which Lukaku forced to watch on.
Lukaku has scored three goals under Solskjaer but now appears to be behind Rashford in the pecking order.
And Redknapp believes Lukaku must be wondering about his future amid Rashford improved form.
Lukaku having an Alonzo Mourning moment pic.twitter.com/FSf1JwTqt5
— amadí (@amadoit__) January 13, 2019
“For the first time in his career, Marcus Rashford is playing like he truly belongs in a Manchester United shirt,” he wrote in his Daily Mail column.
“Earlier in the season he was in and out of the team and that led to inconsistent performances in front of goal. He looked better for England than he did for United.
“Ole Gunnar Solskjaer has put his trust in Rashford, given him a run in the team and is now reaping the rewards.
“There is a swagger, an arrogance about the way Rashford leads the line. He no longer hesitates when put through on goal.
“As he raced on to Paul Pogba’s brilliant pass at Wembley, you could see in Rashford’s eyes that he knew he would hit the net.
“All of a sudden, Romelu Lukaku must be wondering how on earth he gets back into this team.”
After the match, Rashford hailed Solskjaer for the tactical plan created to hurt Spurs.
“We played a slightly different system, but against a team like this it was needed,” Rashford told Sky Sports.
“The other teams we have played have played pretty much the same system so today it was a different game and we played differently and the tactics changed.
“But that is what we have to do to be one of the top teams, we have to adapt. And we keep pushing and improving.”