Initial suspicions were that it could be a cruciate knee injury, similar to those suffered by team-mates Benjamin Mendy and Ilkay Gundogan, and he is reported to have left Selhurst Park on crutches.
There is also concern over Kevin De Bruyne after he was stretchered off in the closing moments following a rash challenge from Jason Puncheon, and Guardiola said he is a doubt for the clash with Watford in two days time.
The Belgium global was initially carried off the pitch on a stretcher with his leg in a brace, but he was soon seen ambling down the touchline with the support of City's medical staff.
And after Gabriel Jesus went off injured today, Guardiola was once again asked about signing Sanchez next month. "Then Kevin we were lucky, well not lucky". I don't know what will happen in the future.More news: Nifty goes above 10500, Sensex in green ahead of F&O expiry
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It proved to be a frustrating day for City, though it could have been a lot worse when Luka Milivojevic stepped up to take a penalty after Raheem Sterling was adjudged to have fouled Wilfried Zaha in the box.
That City performed below the extraordinary level they have consistently achieved this season meant that they dropped points in the Premier League for only the second time in 21 games, and for the first time did not score. "We were lucky against Tottenham and against Newcastle".
Ederson ultimately saved the spot-kick to preserve City's unbeaten run and, while some have accused the Palace winger of going down too easily, Guardiola was content to take the word of referee Jon Moss. Maybe it was a penalty, the referee made that decision so that's okay.