MINNEAPOLIS -- Minnesota Twins pitcher Phil Hughes has a broken bone above his left knee that's expected to require six to eight weeks to heal, raising doubt about whether the struggling right-hander will return this season.

Manager Paul Molitor said Saturday before the game against Boston that an MRI test on Hughes revealed the fracture, an injury caused by a line drive that hit him on the leg Thursday against Miami. Initial X-rays on Hughes showed no break, but the 29-year-old needed help walking off the field after he was struck.

Hughes will need crutches to walk in the meantime. After the bone has healed, he'll need time to work his arm back into pitching shape, which could push the timetable deep into September.

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Hughes is 1-7 with a 5.95 ERA.