OXFORD United must keep hold of their best players this summer to sustain a promotion challenge next season, says Karl Robinson.

Attention is already turning to 2021/22, after successive defeats over the Easter weekend left the U’s six points adrift of the Sky Bet League One play-offs with seven matches left.

Robinson revealed this week he wants to sign former loanee Marcus McGuane from Nottingham Forest on a permanent deal, but ensuring key figures remain at the club is also important.

Within the last two years, United have sold Gavin Whyte, Shandon Baptiste, Tariqe Fosu and Rob Dickie to Sky Bet Championship sides.

Read also: Oxford United boss confirms Marcus McGuane interest

This week, goalkeeper Jack Stevens has been linked with Middlesbrough, while the U’s rejected Millwall’s offer of more than £500,000 for Cameron Brannagan in January.

And Robinson knows his stars must stick around to prevent United starting slowly for a fourth successive season.

The U’s head coach said: “We’re getting a lot of work done on and off the pitch at the moment, but people only ever see the results that are good, bad or indifferent.

“Work’s going on behind the scenes for next season, but the likes of Jack, Cameron and Rob Atkinson have to stay here next year.

“If you look at the top teams, there’s no turnover of players, they’ve only got better.

“That’s a big learning curve for us for next season.

“Unless the transfer fee becomes something that we have no control over, we’ve got to be really brave in keeping all of these players moving forward.”

Read also: Karl Robinson reflects on familiar failing for Oxford United

Brannagan and Atkinson’s deals run until 2023, while Stevens signed a new contract in February that keeps him at United for another three years.

The 23-year-old has impressed on several occasions in his breakthrough season and Robinson feels the attention is deserved.

He said: “It’s a tremendous credit to him, Browny (goalkeeping coach Wayne Brown) and Easty (Simon Eastwood).

“As a group they’ve forced better performance levels out of each other.”