Arsene Wenger today revealed that it was only a longer than expected injury to Kieran Gibbs that led Arsenal to sign Nacho Monreal.
Gibbs sustained a problem in Wednesday's 2-2 draw with Liverpool, after which Wenger claimed the left-back would be unavailable for just three weeks, report the Evening Standard.
However, tests have shown the injury to be more severe than first thought, with the thigh problem ruling Gibbs out for up to six weeks, prompting the Gunners to move for the Malaga player with Andre Santos the only available left-back at the club.
The 26-year-old joined the Gunners just before the transfer window closed last night on a four-and-a-half-year deal for a fee in the region of £10m.
"Our scouts have followed his progress for a while and, of course, we had a blow with the Gibbs injury, which will keep him out a bit longer than expected," said Wenger. "We expected two to three weeks but it will be four to six, so we were in a position where we had to make a quick decision.
"We bought him as a left-back but he can play, as well, as a left-sided midfielder. We bought him, as well, because we believe he can integrate our style of play and adapt very quickly to that.
"He has the characteristics to play our game because he is very mobile, he has a good left foot and is good in combination play. It is, of course, vital in our style of play.
"What we want him to do is to take part in our collective game and not expect anything individually because our game is based on team play and he has been chosen because he can integrate that."
Nacho will go straight into the squad for tomorrow's Premier League home match against Stoke, and Wenger will be tempted to throw him into action with Santos heavily criticised by some supporters.
The Brazilian's popularity remains low after he was seen swapping shirts with former Arsenal striker Robin van Persie during half-time of Manchester United's 2-1 win in November.
Santos is greeted with a mixed reception every time he plays but he could yet perform a pivotal role in the club's Champions League campaign. Nacho is cup tied having represented Malaga in the competition this season and with Gibbs unavailable, Wenger has only Santos and a makeshift alternative in Thomas Vermaelen as candidates to play at left-back against Bayern Munich.
Wenger added: "Santos has a future at the club, why not? Maybe people speak that he had a difficult game [against Liverpool] but he lacks competition. He is a style of player who needs competition because he is not a nervous type, he is a stamina type of player and get will sharper through competition.
"The criticism he gets is unfair because if you watch the game again and you analyse very well his performance, you will be less critical.
"The first critics after the game are always a bit emotional because you have one or two big mistakes in your mind and we are all the same on that front. But when you watch the games again, you will see that he has done some good things.
"Honestly, I believe that Kieran Gibbs will be out for the Champions League because we are not even three weeks away from Bayern now.
"So I will not play Nacho and certainly not Gibbs but if you want me to tell you who will play, today I can't tell you!
"Vermaelen can play in that position as well. Santos could have a key role as well."
Wenger revealed Arsenal were close to signing one more player, having been heavily linked with Barcelona striker David Villa and West Ham midfielder Mohamed Diame but insists he is happy the squad can achieve their targets despite only adding Nacho.
"We were close to one more signature," said Wenger. "It did not happen because of the desires of the clubs to sell or not to sell. It is only linked with that.
"It was not a money problem, it was more a desire from other clubs to keep their players. I believe that we have top quality in our squad and that is what we want to show until the end of the season.
"We have some aspects in our game that we need to improve and how active we will be in the market in the summer will be decided how well we do now until the end of the season."
Abou Diaby is available for tomorrow's game, while Mikel Arteta faces a fitness test on a calf problem and Vermaelen is a doubt with an ankle injury but Francis Coquelin (hamstring) is still out.