Martin Rivero was just getting comfortable in the Chivas USA midfield.
After just seven matches played for the Goats, the Argentine will be out for a while after the club announced on Friday that Rivero tore his right ACL in last weekend's 1-0 win over Real Salt Lake.
In a club statement, Chivas USA indicated that a date for surgery and a full prognosis will be determined at a later date.
Rivero was only acquired three months ago on April 10 from the Colorado Rapids in exchange for a 2015 fourth-round SuperDraft pick.
He joined the Colorado Rapids in 2012 and starred in 30 matches in his debut season in MLS. A right foot fracture suffered in the 2013 preseason limited him to just 16 matches last year.
Chivas USA's first game without Rivero comes on Saturday when they face the Montreal Impact at StubHub Center (10:30 pm ET, MLS LIVE).