Fabregas scored twice in Barca's 4-1 win over Betis on Sunday, taking his tally for the season to five goals in all competitions.
The Spain international midfielder was substituted 10 minutes from time because of injury, but Fabregas insists the problem is not serious.
"It will not be serious. Just a minor annoyance," he told Canal +.
"I had a major injury in the region not long ago, so I preferred to come off the pitch early. I was already not comfortable against Milan (in the UEFA Champions League on Wednesday)."
The 26-year-old has made 18 appearances for Barca this season, but he does not believe he is in Martino's ideal starting XI.
Fabregas, however, is hopeful that his performance against Betis will help change his coach's mind.
"I know that I'm not in it (Martino's starting XI), and I know I have to work hard to change his opinion," he explained.
"I always try to do what the coach asks me.
"I wanted to vindicate myself, I had a good performance against Celta (Vigo), then there were two games where I was on the bench and that bothered me.
"So I had to play a game like this to assert myself."
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