The Scotland international has fallen behind summer signing Oleksandr Zinchenko in the pecking order this season, making only five Premier League starts.
Standard Sportunderstands the former Celtic defender would be open to joining Newcastle this summer should regular first-team football continue to prove hard to come by.
Eddie Howe’s side are interested in a move for the 25-year-old as they attempt to bring in a recognised left-back ahead of next season.
Leicester were interested in Tierney but saw a January offer snubbed and the player was happy to remain part of the title challenge in north London.
Arsenal are in a strong bargaining position should Newcastle firm up their interest.
Tierney has over three years left on his contract and the club will be looking for more than the £25m they paid to sign him in 2019.
Sagna, however, believes there is still hope for Tierney at the Emirates Stadium but urged him to fight to win his place back.
“I wouldn’t leave the club,” he told sportingpost.com.
“He needs to fight to play and come back into the manager’s plan. He is part of what’s becoming one of the best clubs in England, so where is he going to go?
“Of course you want to be able to play but sometimes you need to be out of your comfort zone, and he’s out of his comfort zone now. So it’s time to fight, not just leave and give up.”
“What’s the point of going somewhere where you know that you’re going to start no matter what, and you’re going to play – you’re not going to progress in that environment.
Challenge: Zinchenko’s arrival has limited Tierney’s game time
/ Arsenal FC via Getty Images“I had the same choice when I left Arsenal, because I was playing in a comfortable position. I could have stayed and yes, I was playing. But at some point, if you want to try and get better and you want to challenge yourself, you need to be out of your comfort zone.”
“Zinechenko is giving him a challenge to fight for his place, so he has to train harder and get back to his very best level so he gets his opportunity and then he has to take it. If he does that he won’t be spending so much time on the bench.”
