Barcelona coach Ernesto Valverde expects Manchester United to challenge for the Champions League in 2017-18.
United finished sixth in the Premier League last season but returned to UEFA's elite club competition courtesy of their victory over Ajax in the Europa League final.
They have since strengthened their ranks by signing defender Victor Lindelof and striker Romelu Lukaku from Benfica and Everton respectively.
And Valverde, whose Barca side defeated United 1-0 in an International Champions Cup match in Maryland on Wednesday, believes Jose Mourinho's team can pose a threat in Europe this term.
"Obviously it hasn't [gone] well [for them] lately, but I mean they won the Europa League," he said.
"This year they are going to be in the Champions League. Their presence by itself is impressive. They impress. I think they are going to be a really hard team to beat.
"For me, they are contenders to win and they are going to be hard to beat in the Premier League and the Champions League.
"I wouldn't want to face them in the Champions League."