Rivas will start at third base and bat ninth in Monday's game against the Athletics.
Rivas will cover the hot corner for the third game in a row and could be in line for a regular starting role for at least the next week after Seattle placed Brendan Donovan (groin) on the 10-day injured list Monday. The 28-year-old hasn't provided much reason to get excited about his fantasy prospects; over 61 plate appearances on the season, he's hit just .143 with no home runs, no stolen bases, four runs and four RBI.