Lopez, who leads the team with 42 RBIs, left the club before Thursday's game against San Diego to return to his native Venezuela because his sister is seriously ill. Mariners manager Don Wakamatsu said he didn't expect Lopez back for at least five days.
Seattle was already without home run leader Russell Branyan, who was attending his grandfather's funeral in Georgia on Thursday. Branyan is expected to return for Friday night's game against Arizona.
Woodward's contract was purchased from Triple-A Tacoma. To make room for him on the 40-man roster, the Mariners transferred pitcher Carlos Silva to the 60-day disabled list.