COMMENT: He's talked it up. He's put on a brave face. But this preseason tour for Manchester United has left their new manager frustrated - and his anxiety levels are at fever pitch...

Undefeated in Thailand and Australia. Three wins from four games. It's great reading for Erik ten Hag. The form of Jadon Sancho. The attitude shift of Anthony Martial. The positive introduction of Tyrell Malacia. There's so much for Ten Hag to be happy about.

But there's a glaring void in all this. And yes, it's connected to the non-appearance of Cristiano Ronaldo. But it has more to do with those running United's summer market campaign than the so-called reluctant Portuguese.

Malacia has arrived to drive Luke Shaw at left-back. Lisandro Martinez is expected to play alongside captain Harry Maguire in the centre of Ten Hag's back four. And Christian Eriksen will offer his trademark guile and creativity to a midfield which struggled for such qualities last season.

But up front, United are bare. At least, when it comes to an Erik ten Hag attack. Martial. Marcus Rashford. They have the striker moniker next to their names. But they don't offer what is regarded as the lynchpin to Ten Hag's attacking structure.

The Dutchman likes a centre-forward. Indeed, his system relies upon one. Through his time in Holland, Ten Hag has always counted on one, if not two, centre-forwards within his squad. And we mean real centre-forwards. Powerhouses. Steamrollers. Goalscorers who are great in the air. Who can play with their back to goal. And who can compete physically with any type of centre-half they come up against.

"I think it's vital if you want to get success, the season is really long," declared United's manager last week when asked about a striker signing.

"That is a reason, but also the number of games. You need more options in offense. But we also have still time to fill that in."

At FC Utrecht, Ten Hag had Sebastien Haller before his sale to West Ham United. The pair would be reunited at Ajax, where the Frenchman simply picked up from where he left off at the Galgenwaard.

While waiting to work again with Haller, Ten Hag worked with Klaas-Jan Huntelaar, the former Real Madrid centre-forward, at Ajax. Kasper Dolberg was there also. And Ten Hag helped bring through Lassina Traore before his sale to Shakhtar Donetsk.

As we say, Ten Hag likes a centre-forward. Which is why he's spoken so openly about counting on Ronaldo this season. This isn't bluff. This isn't the United manager playing it coy. Ten Hag is genuine when he says he expects Ronaldo to start the new season in a United shirt.

For this column, we're with him. We haven't heard anything new from those we trust since the end of last season. Jorge Mendes may be putting it about in the press. But inside the club, there's a belief Ronaldo will remain a Manchester United player this new season.

Of course, the Atletico Madrid speculation has been raised. But Enrique Cerezo, the club's president, has already knocked this on it's head. Talk in the English press of a complicated deal involving Antoine Griezmann doesn't quite chime given the Frenchman remains a contracted Barcelona player. Cerezo has no call on selling the striker - even if he and coach Diego Simeone wanted to... which they don't. Sending Griezmann back to Barca is also a non-starter with the second of this two season loan already signed off back in May.

So, if we're to believe those wantaway reports, Ronaldo is stuck. Or, as we've been told, Ten Hag will welcome a fresh and motivated Ronaldo to training this week. Though it must be said, United's No7 will need to fix some fractures between himself and the support. As much as he's kept his own counsel, the speculation swirling around him and Mendes has left United fans frustrated.

It's a feeling shared by Ten Hag. He's lost three weeks without the one centre-forward his squad boasts. And they'll have less than a fortnight together before the Premier League kickoff against Brighton. This isn't what Ten Hag had planned.

Nor is it when it comes to the market. The manager wants two attacking additions made before the window shuts in just over five weeks' time. His former Ajax striker Antony is a confirmed target. And there remains a belief a deal will be done, despite the claims of Ten Hag's successor at Ajax, Alfred Schreuder.

But the Brazilian will arrive as one to face the goal. Ideally to play off and around Ronaldo. As we say, Ten Hag wants more. He wants an out-and-out centre-forward. United's late attempt to intervene in Liverpool's deal with Benfica for Darwin Nunez is proof enough of that. Throw in the approach to the minders of VfB Stuttgart centre-forward Sasa Kalajdzic and you can see Ten Hag's line of thinking.

As he said, "we still have time", but United's front office need to get a move on - and deliver. Even if Ronaldo does turn up this week fully committed, Ten Hag's squad remains short of the one player he needs to get his ideal system up and firing.

It's been a good preseason tour for the new manager, but his anxiety levels won't ease until that new centre-forward walks through the club's Carrington gates.