Competition is healthy in football, look at Patrice Evra, who has let his standards slip badly over the past two years. Sir Alex Ferguson has brought in young dynamo Alexander Buttner to compete for the position, and the Frenchman will now have to up his game if he is to be sure of a starting place.
Judging by the reaction of fans to Buttner's performance at the weekend, they are thrilled there is a battle for places at long last.
Ask them about the goalkeeping situation, and it will be a different matter. Hesitant glances and split opinion. Anders Lindegaard and David de Gea have been battling it out for more than a year for the first team spot, and still the first choice is unclear. Lindegaard even commented this week that the pair 'share it.'
Is that competition a good thing? While no player in any position should be complacent, you only have to look at results from last season to see that United's best run came when they had a settled line-up.
From March to April the club kept a string of clean sheets, with De Gea in goal and Lindegaard injured. Previous to that there was too much inconsistency, both in team selection and performance levels.
Whether it cost them in the league is debatable, but it certainly upset their Champions League run, and saw them eliminated in the group stages of the competition. This season the battle for the position has reared its head again, with Lindegaard fully fit and De Gea dropped after making a single mistake. So much for sticking by your man.
The reason this is relevant to Arsenal, is because there is a similar issue on the horizon for their goalkeeper's jersey.
After years of indecision, see the battle between Jens Lehmann and Manuel Almunia, not to mention the Lukas Fabianski experiment, Arsenal finally had their number one land at their feet, with Wojciech Szczesny rising through the youth ranks.
Vito Mannone is a youngster who had an early taste of action, even prior to the Pole, but was sent on loan to Hull twice to gain experience after being judged too raw.
A surprise injury to Szczesny has seen Mannone recalled to the first team, and thanks to the Gunners new-found defensive solidity, he kept clean sheets in away games to Stoke and Liverpool, impressing with his composure, even if there wasn't a great deal of shot stopping to do.
A fit again Szczesny was recalled for the Southampton mauling, but made an uncharacteristic lapse in concentration to concede the club's first league goal of the season last weekend. Another injury saw Mannone brought in for the Champions League game at Montpellier, and he now claims he has been given the green light by Arsene Wenger for a run at claiming the number one spot.
Questions have been asked over how long Szczesny will be out for, still unclear, and whether the Pole is becoming too sure of himself too soon, see his recent error plus his mistake at Euro 2012 for Poland.
Harsh? Perhaps, but Wenger clearly feels, like Ferguson, that competition is healthy and has no reason to discourage Mannone, a young talented goalkeeper with a lot to offer.
Even supporters, used to the idea of Szczesny as number one, are beginning to wonder if he could be toppled, or at least challenged fiercely for his place.
While the Gunners were inconsistent last season, in goal he was their sure thing, one of the most reliable members of the squad. If that were to change, Arsenal could find themselves in the same situation as United, unsettling the defence.
Clearly there is nothing the club can do about injury, and it is great they have a good stand-in to step up, and if he stakes his claim, then Mannone has every right to be considered for the number one spot.
But when both players are fully fit, Wenger will have to choose one and stick with him, rather than fall into the same trap as United and end up routinely flitting between the two from one game to the next.
image: © Ronnie Macdonald