A transfer window that provided plenty of early encouragement for Manchester United is in danger of petering out in frustration. Still seeking reinforcements at both ends of the pitch before the window shuts on Sept. 1, it became clear on Wednesday that Barcelona forward Pedro, who had seemingly been on the verge of completing a move to Old Trafford for more than a week, was instead heading for a medical at Chelsea.

United have portrayed it as manager Louis van Gaal turning his back on the deal, but, regardless of whether that is wholly accurate, it leaves the Premier League giants in a difficult position. As well as resolving the ongoing saga over David de Gea’s potential transfer to Real Madrid, it leaves Van Gaal and United executive vice-chairman Ed Woodward with plenty of work to do to further strengthen a squad expected to challenge for the Premier League title. While United have a perfect record in three matches so far this season, there has already been ample evidence that it would be a major risk not to bolster the team’s attacking options.

Thomas Müller  (Bayern Munich)

As reports were emerging of Pedro being on his way to Chelsea, German tabloid Bild was claiming that Manchester United have made a massive bid of 85 million euros (£60 million) to try and land Bayern Munich’s Müller. The rumor of United’s interest has been there for a while. And, given Müller’s versatility and on-pitch intelligence as well as the fact that it was Van Gaal who gave the 25-year-old his first-team breakthrough while in charge of Bayern, it is easy to understand the appeal. Getting the Germany international in a Manchester United shirt, however, is another matter entirely.

Having already sold one symbol of the team, Bastian Schweinsteiger, to United this summer, it would be extremely difficult politically for Bayern to sell another. And in his latest comments sporting director Matthias Sammer has again ruled out the player’s sale.

“It is not Thomas causing a stir, but his performances. We can’t do anything about that. [chief executive] Karl-Heinz Rummenigge is right, he is a player for which there is no price tag.”

Harry Kane (Tottenham)

Perhaps a similar player in terms of style to Muller, in that without appearing to do anything outstandingly he is extremely effective. Kane’s record is a much shorter one than Muller’s, however, having only been a starter at Premier League level for less than a year. His first season, though, made him an instant star, with 31 goals for Tottenham and a goal on his debut for England. Manchester United appear convinced that the 22-year-old is no one-season wonder and, according to reports, are willing to pay up to £45 million to bring him to Old Trafford.

Yet it appears so far that United have been merely exploring the possibility of a deal for Kane without actively pursuing it. And they would be right to be wary of getting into a full-blown pursuit with notoriously tough-negotiating Tottenham chairman Daniel Levy. Already short of strikers even with Kane’s presence, Tottenham will know that cashing in on Kane, a homegrown hero, would bring outrage from the supporters.

Karim Benzema (Real Madrid)

Under Sir Alex Ferguson Manchester United regularly tried to lure Benzema to Old Trafford, even dating back to his time at Lyon. While more recently he has been strongly linked with a transfer to United’s Premier League rivals, Arsenal, United have still been suggested as a possible destination. And it is easy to envisage their interest increasing after missing out on Pedro.

While Benzema is a very different player to the Spanish winger and plays predominantly through the middle, he also has shown the technical ability to play across the forward line. And given Wayne Rooney’s poor start to the season, it can’t be ruled out that Van Gaal will consider moving his captain into a deeper role and recruiting a world-class striker in Benzema’s mold. So far, though, there has been little indication that Real Madrid are willing to sell. Manger Rafa Benitez has insisted the France international is very much in his plans, and, with less than two weeks of the transfer window remaining, Madrid would have precious little time to get in a replacement. Still, Madrid’s interest in getting De Gea could potentially play to United’s advantage.

Edinson Cavani (Paris Saint-Germain)

Cavani is another striker to be linked with both Arsenal and Manchester United. There has been plenty of speculation over the Uruguay international’s future for much of his time at PSG, with the player unsettled at being shunted out wide due to the presence of Zlatan Ibrahimovic. Yet with the Swede now aged 33 and with his future in question, now would appear a strange time to part ways with Cavani.

While the former Napoli star has missed chances in some big games for the French champions over the past two years, he finished last season strongly. And it was only recently that PSG’s president insisted that Cavani was not for sale.