In one of the summer transfer window's most surprising twists thus far, Chelsea snapped up Pedro in a £21million deal last week despite the Barcelona winger being linked with a move to Manchester United practically since the end of the 2014/15 campaign.

Indeed, chief executive Ed Woodward even flew out to Barcelona last Monday to try and accelerate the negotiation process. But by Wednesday, Louis van Gaal had 'dropped all interest' in the 2010 World Cup winner and by Thursday he'd become an official Chelsea player.

It makes you wonder what changed the Old Trafford gaffer's mind at the last minute; or perhaps more importantly, what he has planned next. Manchester United have never been the kind of club to target one player at a time, so did a better option become available?

At this point in the transfer window it's certainly a plausible theory - one that Football Fancast feel compelled to examine deeper. And thus, we've listed five equally or arguably more talented wide men the Red Devils might have up their sleeve.

SADIO MANE

Let's start with what we already know. According to reports from The Telegraph, Manchester United are expected to launch a bid that exceeds the £20million mark for Southampton's Sadio Mane before the end of the transfer window.

The Senegal international has certainly impressed since arriving at St. Mary's last summer, netting ten times during his debut Premier League campaign and recording the fastest hat-trick in the division's history during a 6-1 thumping of Aston Villa.

Likewise, United's current forward line lacks penetrative pace but that's easily the 23 year-old's greatest asset, last season averaging just shy of two successful dribbles per match and carving his way through Premier League defences on a weekly basis.

Is Mane truly of Manchester United quality, however? That remains open to debate. Meanwhile, Saints boss Ronald Koeman has insisted none of his players will be allowed to leave the club at this point in the transfer window.

NICOLAS GAITAN

Manchester United's need for another winger is predominantly due to the sale of Angel Di Maria. So who better to fill the now-PSG star's void at Old Trafford than the man who replaced him at Benfica in 2010? Namely, Nicolas Gaitan.

The 27 year-old is perhaps a little less dynamic than Di Maria, lacking his penetrative pace, all-round energy and netting prowess, with just 30 goals in 216 appearances for the Primeira Liga outfit.

But the Argentina international boasts equal Albicelestial talent in many regards, particularly their shared ability to operate almost as playmaking widemen; proving just as proficient when drifting inside as when launching testing deliveries from the touchline.

Gaitan has been linked with a move to the Premier League - and particularly Manchester United - for much of his Benfica career and the rumours have emerged once again this summer.

Reports from The Daily Star yesterday evening claim 'Super-Agent' Jorge Mendes, of Cristiano Ronaldo and Jose Mourinho fame, has been brought in to try and broker a £24.5million deal.

But without a release clause in his contract, United face a tough task of convincing Benfica to sell their only remaining true top class talent with not much of the window left to find a replacement.

KARIM BELLARABI

Every speculative list of this variety should include a wildcard mention and mine comes in the form of Bayer Leverkusen star Karim Bellarabi.

He's by no means a household name and will sound only vaguely familiar to those who don't dabble their footy interests too far past the Premier League, having made just a handful of appearances in European competitions and for the German national team thus far.

But the 25 year-old was absolutely phenomenal for Bayer last season, amassing twelve goals and six assists in 33 appearances whilst averaging the most successful dribbles per match, a whopping 4.7, of any player in the Bundesliga, and most importantly for Manchester United offers frightening speed and strength from the flanks.

He also recorded the rather incredible feat of the fastest goal in the Bundesliga's history, both in terms of a season and a single game, netting in just nine seconds against Borussia Dortmund (more on them later) during the opening fixture of the 2014/15 campaign.

Despite that being enough for explosive winger to worm his way into Joachim Lowe's plans for Die Mannschaft, picking up seven caps since his debut last October, Bellarabi still represents a bit of a punt for the Red Devils.

But with a release clause of a meagre £11million, in my opinion it's probably a punt worth taking. That buy-out fee also means that United won't have to barter with Bayer, which will save them an invaluable amount of time as the summer window reaches its final stages.

ANTOINE GRIEZMANN

Reports linking Manchester United with Atletico Madrid's Antoine Griezmann are certainly intriguing, because the versatile forward would not only address their limited options out wide but also the need for a centre-forward who can compete with Wayne Rooney at No.9.

Indeed, the France international arrived at Vincente Calderon last summer after reaching talismanic levels as a hardworking, goalscoring wide man for Real Sociedad, playing an intrinsic role in their rise from the Spanish second tier to the Champions League in the space of four seasons.

But since joining the Mattress Makers, Griezmann has reinvented himself almost as an out and out poacher, last season bagging 25 goals in all competitions and finishing third in La Liga's scoring charts behind Lionel Messi and Cristiano Ronaldo.

Famed for his pace, technical ability and a tenacious streak that's seen him flourish under Diego Simeone, the 24 year-old seems likely to acclimatise to the Premier League very quickly, whilst he certainly fits Louis van Gaal's preferred mould of adaptable, 'multifunctional' footballers.

The bad news is that Griezmann signed a new contract with Atletico just last week, suggesting the club will be in no mood to sell. The good news, however, is that it included a £56.5million release clause.

Certainly not cheap for a player still limited in terms of top level experience; but an affordable price for United at this point in the transfer window.

MARCO REUS

Borussia Dortmund have done sensationally well to fend off interest in all of their top talents this summer, despite failing to qualify for the Champions League at the end of last season and resultantly parting with the man who masterminded their recent renaissance, Jurgen Klopp.

But if there's one Black-Yellows talisman who could still be whisked away before September 1st, it's almost certainly winger-forward Marco Reus.

He signed a new contract in February to eradicate his previously £25million release clause. But undoubtedly one of the most exciting attackers in world football, it seems inevitable a last-ditch approach will be made by an elite club this week.

Indeed, the 26 year-old has produced 37 goals and 27 assists in 82 league outings for Dortmund and won the German Footballer of the Year award twice in the last four seasons - the first coming after his scintillating form at former club Borussia Monchengladbach, which paved the way for a Westfalen move in summer 2012.

Reus is an extremely versatile forward of fantastic technical quality, equally adept at the roles of scorer or provider and comfortable in any role across the attacking midfield berth or spearheading the attack as a centre-forward.

But that's all underpinned by the German international's lightening pace which, for reasons aforementioned, makes him probably the best candidate on this list from United's perspective.

The only problem, however, is that Dortmund now hold all the cards. If they're to part with Reus before the close of the window, it will be for an astronomical fee.