Summer signing Sibley, who arrived from Derby County as a free agent, has founded chances hard to come by at United so far, making just two Sky Bet Championship appearances prior to the trip to Fratton Park.

He made an immediate impact though, replacing Ruben Rodrigues from the bench and equalising from the edge of the penalty box in the 72nd minute, having only entered the game moments earlier.

The draw was a third on the bounce for the U’s, with points also picked up against Burnley and Luton Town.

United head coach Buckingham said: “I’m happy with that. Of the nine games we’ve played, we knew this week was going to be a tough run-in.

“We managed to get points from both of those former Premier League games, and then we knew coming here, especially after watching them on Wednesday, the reaction they would try to give.

“It was a wonderful atmosphere, and the crowd tried to get behind them to keep going. It’s now making sure that on the road, we pick up points and hopefully that transfers to our home form, which will put us in a good space.”

He added: “We’re really delving into our depths at the moment. I’ve just spoken to the players in there, and it won’t always be pretty every game, and we won’t always be able to play the way we need.

“What I’m really happy with is the ability to match a very good Portsmouth side physically and otherwise away from home in a great atmosphere.

“The players that have come on, we spoke about how important our depth was going to be.

“A special mention to Louie Sibley, who has had to be patient all season, and watched others go on before him.

“He’s been very patient to take his chance when he got it. To bring him on, it was a wonderful finish from Louie.

“I see it every day in training with the goalkeepers within the shooting practices telling him to take a little bit off because he’s got a sledgehammer of a foot.

“I think that sums up the togetherness of this group, and how important squad depth is to us at the moment when we’re missing seven or eight players that have started for us this year.

“The international break comes at a good time, but we go into it off the back of a good run, and we’ll look forward to welcoming West Brom at home.”