CHESTER, Pa. – Sebastien Le Toux was excited to start at fullback for the first time in about eight years and come to the aid of the Philadelphia Union’s beleaguered backline over the weekend.

But the Frenchman’s rare defensive appearance was quickly spoiled when, in the first minute of Saturday’s game against D.C. United, he felt a pop in his right foot where he had been dealing with plantar fasciitis. And after just 16 minutes, he was forced to come out of the game, with deep reserve Matt Kassel taking his place.

Now, Le Toux is just trying to get healthy enough to play in Saturday’s critical contest against the Montreal Impact (2 pm ET, MLS Live) at Saputo Stadium – but it’s not looking especially promising.

“Right now at this moment, if the game was tomorrow, I can’t play,” said Le Toux, following the Union’s training session Tuesday, of which he did not participate.

Le Toux said his foot issues began after the Union’s 1-0 loss to San Jose on Sept. 8. He’s tried to manage the pain since then but noted that “every time after a game it was getting worse.” An MRI later revealed that he had a partial tear of his right plantar fascia – which he believes became “completely torn” after he planted his foot the wrong way and heard a pop at RFK Stadium on Saturday.

“I’m getting treatment and wearing a boot most of the time when I’m home,” Le Toux said. “It sucks. I can’t really run.”

With Fabinho and Sheanon Williams both set to return after one-game suspensions, the Union won’t need Le Toux on the backline for the final two games of the regular season. But they’ll be hard-pressed to find a better winger, where Le Toux has a team-leading 12 assists and has played most of his 2,202 minutes.

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And even though his playing time has fizzled over the past three games because of the injury, Le Toux hasn’t missed a game since April – a streak that could end in Montreal.

“It’s much better than it was two days ago but I’m still feeling it,” Le Toux said. “I’m definitely questionable for this weekend. It’s kind of day-to-day. I could feel better tomorrow but there’s stuff I can’t do like cutting, which still hurts a lot. This has never happened to me before so I don’t know what to expect.”

Dave Zeitlin covers the Union for MLSsoccer.com. E-mail him at djzeitlin@gmail.com.