Nicolas Pepe has been warned that his place in the Arsenal team is at risk by Willian's arrival.
Former Gunners forward, Alan Smith, told Sky Sports that Pepe needs to "kick on" if he's going to "survive".
Willian's move to the Emirates was confirmed on Friday, following his departure from Chelsea.
The Brazilian has put pen to paper on a three-year deal worth around £100,000-a-week.
Smith believes the 32-year-old will boost Mikel Arteta's attacking options next season, but has warned Pepe he could fall down the pecking order.
"One thing is for sure, as a right-sided attacker, his arrival asks immediate questions of Nicolas Pepe, signed at an exorbitant cost this time last year.
"The Ivory Coast winger has blown hot and cold so far, which is not a great quality in Arteta's book. Undoubtedly talented, Pepe has got to kick on if he's going to survive because, in the short term at least, Willian can provide great know-how and quality on that right side," Smith said.