Diego Forlan writes a weekly column for The National, appearing each Friday. The former Manchester United, Inter Milan and Atletico Madrid striker has been the top scorer in Europe twice and won the Golden Boot at the 2010 World Cup. Forlan’s column will be written with the assistance of European football correspondent Andy Mitten.

It’s going to be very difficult for Manchester United if they want to challenge for trophies this season with only one quality striker.

Wayne Rooney is good enough to play in almost any team in the world: he’s experienced, the club captain, who I’m told trains harder than any other player, but my old club need more than one natural goalscorer if they want to win a trophy in 2015/16.

They have very good creative players such as Juan Mata, Memphis Depay, Ander Herrera and Ashley Young. They look like they’re going to sign Pedro, from Barcelona, and that will be a wise addition. But while the creative players will chip in with their share of goals, they’re not the natural-born finishers who live and die by how many goals they score, the predators who play on instinct and just know where the goal is.

The creators and playmakers can play well and be satisfied with their performances despite not scoring, but if you’re a striker, you’re never fully happy until you’ve found the net. I know, I’ve spent all my professional life like that. The strikers will have the best scoring rates, they’ll convert more chances and they’ll have certain attributes that makes them the centre point of the team. It might be electric pace, great heading ability or a knack for knowing where the goal is. It might be that they’re good finishers with both feet.

Diego Forlan’s Premier League preview:

Chelsea and Man City battle for title, Man United still lack stars

United have lost Robin van Persie and Radamel Falcao, two great strikers who struggled last season. It was the club’s decision to let them go, but I’m surprised that they’ve not been replaced.

That great United team which won the treble in 1998/99 had Dwight Yorke, Andrew Cole, Teddy Sheringham and Ole Gunnar Solskjaer. Four strikers playing for two places and all four were needed throughout the season. If two weren’t working then there was always the option of another two. They played in a 4-4-2 system and, while United look like the will line up in a 4-3-3 or 4-2-3-1 formation under Louis van Gaal, they don’t need four central strikers because the other attackers will be expected to get at the full-backs, stretch the defence and leave Rooney one on one with a centre-back.

I’ve played as a lone striker and enjoyed it, especially if you have good supporting players around you. But a full season by myself? That would be hard. United need more than one front-line striker.

If United are to challenge for honours, across three or four competitions, then they’re likely to play 55-60 games this season. That’s a huge burden on one player, especially given the way Rooney plays. He covers so much ground, he chases lost causes and balls into corners. I’m sure he loves the idea of playing 55 games and scoring over 30 goals, but it doesn’t matter how fit he is, that’s a very big ask over a season, especially as he’ll also be playing international football with England.

Players also get injured, especially when they play so many games. They pick up yellow cards and get suspended and also have periods when they’re not playing well and need a rest. It’s also good for any player to have competition, to push them, keep them at their best. It doesn’t even matter if they don’t get along — like Cole and Sheringham — that can create tension which leads to healthy competition, which is better for the team. It’s not like they didn’t play well together.

Strikers love to play with other strikers, as I did with Sergio Aguero, Luis Suarez and Edinson Cavani. You can make the most of your individual talents for the good of the team. If you can strike up a good partnership with another player it’s like striking gold.

Of course, strikers usually have the biggest egos; they have the highest highs when they score and the lowest lows when they don’t but, if you get a striker in form it will carry a team forward. Rooney can do that, but it’s a big ask.

If United have three or four goalkeepers then they can certainly have more than one main striker, though in James Wilson they have a promising young talent. United also have Javier Hernandez, though it would appear his future lies away from the club.

Pedro would be a versatile signing who can play in four or five positions, including the central striking role. I understand why United would be an attractive move to the Barcelona forward: United are another huge club who should play — and pay — well. The 28-year-old Spain international should also find it easier to get into a side in transition than a team that already has Lionel Messi, Luis Suarez and Neymar up front.

He’ll move for more game time, which is exactly why I left United, a decision I never regretted. United had Ruud van Nistelrooy, Louis Saha, Solskjaer, Alan Smith and Cristiano Ronaldo when I departed.

Van Gaal may sign another forward, or he may be happy with what he’s got. He may wait to see how United do in the first few games and then decide players to bring in players at the last minute before the transfer window closes, as he did with Angel di Maria and Falcao last year.

Looking for the quick-fix carries risks, though. No matter how good a player is, he’ll need time to settle into a new team, club and country.

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