Erik ten Hag has warned Harry Maguire he must prove he is good enough to merit a regular spot in the heart of Manchester United's defence.
Maguire endured a difficult campaign both on and off the field last season, leading to suggestions David de Gea or Cristiano Ronaldo would take over as United captain.
However, Ten Hag clarified at a news conference during United's pre-season tour of Thailand and Australia that the England international will continue to wear the armband.
That was considered a huge vote of confidence for Maguire, though he now faces additional competition for a starting place with Lisandro Martinez on his way from Ajax.
United have reached a £56.5million (€67m) agreement with the Eredivisie champions for Martinez, who can play in a number of positions but favours playing as a left-sided centre-back.
That would naturally see him play alongside Raphael Varane, with Victor Lindelof also battling for a spot at the back.
While Ten Hag has reiterated he is a fan of Maguire's, the Dutchman is not offering his skipper any assurances heading into the new campaign.
"We have good centre-halves and Harry is one of them. He can play on the left side and on the right," Ten Hag told The Athletic.
"I think he is [a first-choice player]. He's proved it in the past but he also has to prove it in the present time and in the future.
"He has played 46 times for England. Harry is really impressive and I expect a lot from him.
"But there is also internal competition and that is what a club like Man United needs. You cannot win with 11 players. We need a squad.
"Especially this season with so many games. We have the Europa League, the Premier League and the World Cup, so we need a full squad with high-quality players."
Maguire is about to begin his fourth season as a United player after joining from Leicester City in an £80m transfer in 2019, making him the world's most expensive defender.
The 29-year-old has made 144 appearances for United, which is 11 more than next-highest Marcus Rashford during his time at Old Trafford.
However, he started only 75.5 per cent of games in all competitions last season, compared to 85.2 per cent the previous campaign and 90.2 in the 2019-20 season.
Asked about his decision to continue with Maguire as captain, Ten Hag said: "I always see the captaincy as an issue that I dictate.
"The team building for me is an important point and I always talk about a group of leaders. The captain is a really important one and I'm happy with him.
"It can help [give him more confidence]. I will support him everywhere I can. In the end, he has to do it by himself, and he has the qualities to do it."
Maguire was not the only United player who struggled last season, with the Red Devils recording their lowest-ever Premier League points tally (58) and finishing in sixth.
United have won their opening two pre-season friendlies under Ten Hag, against Liverpool and Melbourne Victory, and the new boss is eager to restore his players' confidence.
"You can see that it affects the players. Now we have to cheer them up and motivate them," he said. "We are trying to bring the confidence back.
"That's one of the important points to get success, that you have self-belief as an individual and as a team. That is a process, individual talks for instance, the positive approach.
"Sometimes also you can be highly demanding because that is what we expect and we give them feedback. If they don't, you ask: 'Why are you not acting to your standards?'.
"I want to get the maximum out of the players who are here. I think it belongs to Manchester that you're always looking for better, for competition, because that is a tool to lift, too."
