Although Louis van Gaal has consistently backed his current forward options in the press this summer, particularly captain Wayne Rooney, you get the feeling Manchester United probably need a bit more firepower to be considered genuine Premier League title contenders this season.

The only problem, however, is that the pool of strikers befitting the impeccably high standards at Old Trafford is getting smaller with every passing day of the transfer window.

Mario Mandzukic, Christian Benteke, Carlos Bacca, Jackson Martinez, Paulo Dybala and Luciano Vietto have already been snapped up by new employers, whilst the likes of Pierre-Emerick Aubameyang, Alexandre Lacazette and Mauro Icardi have penned extended terms at their respective clubs.

There's still the best part of three weeks left to go until Jim White's head explodes on summer deadline day, so no need to hit the panic button just yet.

But who left on the market could resolve the Red Devils' limits up top? Football FanCast have decided to take a look...

ANTOINE GRIEZMANN

The interesting case of Antoine Griezmann; the France international who performed a talismanic role as Real Sociedad's hardworking, free-scoring wide man during the club's meteoric rise from the Spanish second tier to the Champions League, but netted 25 times for Atletico Madrid last season upon converting himself into an unorthodox centre-forward.

Indeed, Griezmann is by no means a natural striker and the jury's still out on whether he can be consistent in that position long-term, with just one campaign's worth of evidence thus far.

But no doubt, whether deployed centrally or on the flanks, the 25-year-old would add some much-needed firepower to the Red Devils' attack, whilst his impeccable industry and defence-penetrating speed certainly befits the themes of the Premier League. Likewise, Louis van Gaal loves his versatile 'multifunctional footballers' and Griezmann firmly falls into that category.

Atletico Madrid aren't too keen on the idea of selling the 5 foot 9 attacker this summer, having acquired him from the Anoeta roster only twelve months ago, but they'll have no choice should Manchester United activate his £43.5million release clause. Admittedly, however, that's quite a substantial sum considering Griezmann's played at centre-forward regularly for just one season.

GONZALO HIGUAIN

Following Napoli's failure to qualify at the end of last term, Gonzalo Higuain will be the most talented striker in Europe not plying his trade in the Champions League next season.

The Argentina international is best famed for his profligacy in front of goal, recording of 217 goals in 459 outings from his spells with River Plate, Real Madrid, the Naples outfit and Abliceleste; which tends to see him billed as a somewhat limited fox-in-the-box poacher.

But the 27-year-old's game has more dimensions than you might think. He's claimed eleven assists in 52 outings for his country and 15 over the last two campaigns in Serie A. In fact, he spent as much of last season on the wing as he did at centre-forward for Napoli.

You can already imagine him and Wayne Rooney forging quite the impressive partnership, with both adept in the roles of scorer and supplier.

Napoli have continually insisted any potential suitor must activate the 6 foot striker's £67million release clause. But Higuain rejected a contract extension last week amid reports that he wants to leave the club, and the developing friction between player and boardroom could eventually oblige them to sell for less.

SAIDO BERAHINO

Tottenham Hotspur's Harry Kane is probably beyond Manchester United's reach this summer but they may have better luck with former England U21 strike partner Saido Berahino.

Indeed, Kane is indisputably the most exciting home-grown striker in the Premier League right now but his Baggies counterpart isn't too far behind, netting 14 times in 38 appearances last term for a Hawthorns outfit fighting the drop. He also boasts the third-most goals for England at U21 level; his haul of ten only bettered by Alan Shearer and Francis Jeffers; and was named the age group's Player of the Year for 2014.

Admittedly, Berahino's all-round game is somewhat limited and he certainly lacks vital top level experience when compared to the other names on this list.

But Manchester United have always invested in synergy between their own starting Xi and that of the England national team - signing the 22-year-old would maintain that longstanding tradition. It's believed West Brom are prepared to sell this summer, but only for their £25million valuation.

KARIM BENZEMA

The vast majority of speculation this summer has linked Arsenal with a £45million move for Real Madrid's Karim Benzema but I see no reason why Manchester United can't throw their name into the proverbial transfer hat as well.

After all, the France international seems almost tailor made for Premier League football; with beastly brawn, aerial threat and aggression in abundance; which is why Sir Alex Ferguson attempted to bring him to Old Trafford after becoming one of Euro 2008's breakthrough stars.

The 27 year-old has gone on to claim 133 goals in 281 appearances since joining Los Blancos instead, which perhaps isn't so impressive considering they reach the latter stages of the Champions League and the Copa del Rey final practically every year.

But that's also why Benzema could be such a shrewd signing for the Red Devils; after spending the last six seasons in Cristiano Ronaldo's almighty shadow, he still has plenty to prove and copious doubters to silence.

Although Arsenal are the front-runners in the race to sign the 6 foot 2 Frenchman, a swap deal involving Real Madrid target David De Gea is certainly plausible.

ROBERT LEWANDOWSKI

Bayern Munich have made it abundantly clear they won't be selling Thomas Muller this summer. Robert Lewandowski, however, they might feel more comfortable parting with.

No doubt, the Poland international is one of the best (if not the best) centre-forwards in world football, blending a powerful 6 foot frame with two exceptionally classy feet to conjure up 119 goals in 192 appearances across all competitions over the last four campaigns - including a four-goal haul against Real Madrid at the Bernabeu in 2013.

As an old-fashioned, aggressive front-man used to holding the line on his own, he'd certainly acclimatise to the physical nature of the Premier League and Manchester United's customary lone striker role.

And whilst Muller is a Bayern boy through and through, the Allianz Arena outfit signed Lewandowski on a free transfer from Bundesliga rivals Borussia Dortmund last summer. Should they decide sell after just one year, the Bavarians stand to make an enormous profit.

The 26 year-old's agent believes Bayern would only consider selling for in excess of £35million. But in the grand scheme of things - and indeed, this article - that fee actually represents quite the bargain.