Manchester United face a "long road" before they can mount a Premier League title challenge but signing Frenkie de Jong would make a "huge difference", according to Jamie Carragher.
United have won all three of their pre-season contests under Erik ten Hag, including a 4-0 thrashing of Liverpool in their first outing under the Dutchman.
The Red Devils broke a number of unwanted records during their dire 2021-22 Premier League season, posting their lowest points tally (58) and worst defensive record (57 goals conceded) in the competition's history.
Despite United impressing during their tour of Asia and Australia, Ten Hag warned on Tuesday there was a "lot of work" remaining and Carragher echoed similar sentiments.
Asked by Sky Sports whether he feared United could rival his beloved Liverpool, Carragher said: "I wouldn't say [I'm] nervous.
"I think there's a long road for United that they're on at the moment in terms of challenging for the title.
"I think the first thing when it comes to Ten Hag and the players they're bringing in will be, 'we need to get this club back in the Champions League, where it belongs'. That's where Manchester United should be.
"They're one of the biggest clubs in the world, never mind this country, so to not be in the Champions League just doesn't feel right, not when United are in the Europa League.
"So I think that's the first thing and I think once United do that, then it'll be looking at the title in the next couple of years.
"But it won't be easy to get back in the top four this season – not just for United but for any team who are normally in the top four.
"You'd expect [Manchester] City and Liverpool to do it because they're always going for the title, but you look at how strong Chelsea will be and the signings they're bringing in, Tottenham's work as well, Arsenal also.
"So I think competitively now in terms of getting in the top four, it's really tough, and it's proven that way for a lot of Manchester United managers with great CVs in the past.
"But there's no doubt this manager has a really good CV and they made a really good start in pre-season."
Having already added Tyrell Malacia and Christian Eriksen to their squad, as well as agreeing a deal for versatile Ajax defender Lisandro Martinez, United have been strongly linked with a move for talented Barcelona midfielder De Jong.
The future of the Netherlands international remains uncertain after he was included in Barcelona's squad for a tour of the United States, and Blaugrana president Joan Laporta has repeatedly claimed the Catalan giants do not need to sell the 25-year-old.
Carragher believes De Jong would have a huge impact should he make the switch to Old Trafford.
"It'll be interesting if they get De Jong," he added. "I do think he's a top-class player and I think he would make a huge difference for them."
United's next pre-season outing sees them face Aston Villa in Perth on Saturday, before fixtures against Spanish duo Atletico Madrid and Rayo Vallecano next week.
