Rupture sends Slipper home
He will be replaced on the tour by prop Phil Kite, who trained with the squad throughout the pre-season.
"It's obviously really disappointing for James to suffer such a serious injury this early in the season. We'll miss his contributions on the field, but knowing the sort of bloke he is, he'll still be heavily involved from the sidelines.
"We're fortunate that we've got Stephen Moore in the side, who is the current Wallabies skipper. He will take over the captaincy in Slipper's absence," Reds head coach Nick Stiles said.
The Reds trailed 0-15 at half-time but played most of the second half down a man following a red card to Quade Cooper for a high tackle in the 45th minute. The Lions took full advantage of the extra man, scoring four tries after the penalty to put the game out of the Reds' reach.
"It's a frustrating result because we prepared well, but the performance just wasn't there. We had some good opportunities in the first half but failed to build any pressure. Once we were shorthanded it was always going to be an incredibly difficult task.
"The Lions were runners-up last year for a reason, they're a very good team and they showed that in the second half.
"If there's one positive to take from the match, I was pleased with the effort of the young guys who came on in the second half, they didn't roll over, they had a real crack and will learn from that experience," Stiles added.
