Alex Jackson, the sixth overall pick in this year's Draft by Seattle, was taken for X-rays on Monday after being struck in the face by a line drive during a Rookie-level Arizona League game.
The Mariners confirmed Tuesday that Jackson had suffered a small fracture of the maxillary antrum (sinus area).
"He's doing okay," Seattle's director of Minor League operations Chris Gwynn told the Seattle Times. "It's supposed to be not really too bad. When you think about it, he could have got hit in the eye or other different places that could have been worse. We're having him see our specialist and we'll see where it goes. Right now, we don't think it's that bad. He's going to rest for a while and see some doctors."
The team could not provide a timetable for Jackson's return until he meets with the specialist.
The 18-year-old right fielder was chasing a fly ball into the right-center gap when he slid while trying to make a back-handed play. Jackson appeared to lose the ball in the lights, and the liner hit him on the left cheek.
Jackson landed on his back and remained there for two to three minutes before being carted off the field. The outfielder never appeared to lose consciousness, and no blood was visible. A team trainer drove him to the hospital for X-rays.
The Escondido, California native hit .400 with a 1.459 OPS in his senior season at Rancho Bernando High School. MLB.com rated him the No. 4 prospect eligible for the 2014 Draft.
Jackson played the outfield and catcher prior to being drafted, but has only manned the outfield for the AZL Mariners. In 20 games, Jackson is batting .289 with two homers, six doubles and 15 RBIs. He flew out to right field in his lone at-bat Monday.
Seattle's 2013 first-round pick (12th overall) D.J. Peterson was hospitalized after being hit by a pitch in the face last August, breaking his jaw in eight places. Peterson missed the rest of the 2013 season and was kept out of baseball activities for three months after that.