Former Germany international Per Mertesacker has been a mainstay in Arsenal’s starting XI ever since his arrival to north London in 2011.  The towering center back has averaged 48 total appearances over the last three seasons and played his 200th total match in red and white during Arsenal’s 2-0 defeat at home to Barcelona on Tuesday. While Mertesacker has been extremely reliable in his 4+ years with the Gunners, his time as an automatic starter with the club is under serious threat.

Mertesacker has never been one to possess blazing speed, or any speed whatsoever for that matter.  This lack of pace has left the Gunner defense exposed at times recently, especially against teams with smaller, speedy forwards up front.  The Barcelona match on Tuesday was a good example of this (although it must be said that the Catalan club can pick apart any defense in the world).  Mertesacker made a sliding attempt inside Barca’s half just before Messi struck pay dirt with an easy finish at the 70th minute mark of the game.  Mertesacker’s inability to track back after making the attempted tackle left the Gunner defense wide open at the back.

With fellow center back Laurent Koscielny a no brainer in Arsenal’s starting XI no matter who they face off against, Mertesacker could be set to lose out on his spot to Gabriel Paulista.  The Brazilian defender joined the north London outfit a year ago and has impressed during his short time with the club so far.  Gabriel possesses a solid mixture of speed and strength, and is seemingly gaining confidence the more time he has on the pitch.

The 25-year-old has also won the hearts of Arsenal supporters following his clash with Chelsea’s Diego Costa in September. While the Gunner defender was initially sent off during their 2-0 defeat to their local rivals, Gabriel’s red card was rescinded by the FA.  Gabriel stood up for Koscielny after Costa was seen taking a swipe at the Frenchman.  Following the altercation with the Chelsea striker, Gabriel gave an interview (through an interpreter) on why things went down the way they did that day.   “I will always stand up for the ones I love,” said the defender.

“We have affection for our teammates because we spend most of our time with them,” Gabriel continued.  “Sometimes we spend more time with our teammates than our families.  This is my instinct I always stand up for my teammates.  That’s who I am.”

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Gabriel, however, is not only just a great teammate, he is getting more comfortable and talented as a central defender each time he plays.  During Premier League play this season, Arsenal have kept a clean sheet in seven out of the eight matches in which Gabriel has played a full 90 minutes.

The Brazilian was injured during training at the beginning of the month and has missed the last three matches due to a hamstring problem. However, manager Arsene Wenger issued a statement on Thursday that the defender may be able to feature against Manchester United on Sunday.  “He is coming back into the squad [on Friday], so we will see how he responds to that, but the signs are positive.  He might be available for Sunday.”

A fit Gabriel could mean trouble for Mertesacker.  Though the 6’6” Mertesacker has his faults, he can still be useful in the right situation.  He is technically sound and still a very smart central defender; nevertheless, during most situations, a partnership of Koscielny and Gabriel appears to be Arsenal’s best pairing, both at the moment and for the future.