The winter transfer window opened on New Year's Day and Arsenal figures to be one of the busiest clubs. According to multiple reports, Arsene Wenger is interested in bringing Javier "Chicharito" Hernandez back to England, but Bayer Leverkusen's boss told the French manager that he is not for sale.

Rudi Voller insisted that Leverkusen is not willing to let Hernandez go after arriving in the summer from Manchester United. "We're not selling Chicharito to Arsenal or anyone else. He's not for sale," Voller told Sky Germany via The Daily Star

"Chicharito" was first rumored to be returning to the Premier League at the end of the year as the Mexican was in the form of his career, scoring 19 goals in his first 22 games for the German club. He was named the Bundesliga Player of the Month for both November and December.

According to Spanish newspaper Don Balon per Metro, Arsenal star forward Alexis Sanchez was impressed with Hernandez's form and asked Wenger to sign him. Sanchez reportedly believes that the former Manchester United striker is a great signing for the club and thinks that they can form a great tandem in attack.

However, if the Gunners indeed sign the striker this window, he will not be eligible to play for Arsenal because he has already played for the Red Devils and Leverkusen this season. In a report by The Guardian, Article 5.3 of FIFA's regulations on the status and transfers of players prevents any athlete from playing for more than two clubs in one season.

"Players may be registered with a maximum of three clubs during one season. During this period, the player is only eligible to play official matches for two clubs," the policy stated. Former Newcastle United player Hatem Ben Arfa was the latest to found out about the said rule after completing a move to Nice last January 2015, only to be prevented from playing for the French club.

There is a big possibility that Leverkusen will sell him in the summer and if his form does not change to end the season, he could be sold for at least £25 million, per Bleacher Report. Hernandez was a bargain for the German club as he was bought for only £8 million and helped Leverkusen achieve fifth place in the Bundesliga table to end the first half of the season.

The 27-year-old started his career in Mexico with C.D. Guadalajara then moved to England and play for Manchester United in 2010. He was loaned to Real Madrid last season before being sold to Leverkusen in August.