The Spaniard was handed a rare start against the Championship side by Arsene Wenger, but he was forced off in the 72nd minute of the 2-0 win and replaced by teenager Chris Willock.
If the news of the length of the injury is accurate, Perez is set to miss nine games which includes some huge clashes such as the visit of Tottenham for the North London derby, a Champions League tie with Paris Saint-Germain and the trip to Manchester United.
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Lucas moved to the Emirates Stadium in August for a reported £17.1 million fee on the back of scoring 17 goals in 36 La Liga games for Deportivo La Coruna last season.
Despite failing to nail down a regular starting place, the 28-year-old has rather impressively managed to register two goals and four assists from his six appearances in England, although he is yet to find the back of the net in the Premier League.
The upcoming international break will lessen the impact of his injury on the Gunners, however it means that he's unlikely to play for his new club again until mid-December.
Arsenal's number nine could turn out to be a big miss for them, when you consider that Danny Welbeck is still absent while France striker Olivier Giroud has lacked both form and fitness since returning from the Euros.
Reports of the news spread on Thursday and, as you can see below, Gunners fans took to Twitter to express their opinion after finding out that their summer signing faces an extended period out of action:
Will Arsenal miss Perez while he's out injured? Leave YOUR opinion in the comments box below!
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