It meant uncontested scrums with them being unable to field a complete front-row, and Lam’s team having to lose another player in addition to Lahiff as a result.
“We weren’t getting the rub of the green in the scrums, so we had to change the front-row.
“The boys defended well with 13, but it takes a lot out of you. The scrum is a big part of the game, and fair play to the Bulls.”
Bristol must now beat Connacht in Galway to have even an outside chance of making the last 16, but they are still likely to be reliant on results elsewhere.
Lam added: “The most important thing is to get back into it, get to Connacht and see what happens on the back of that.
“Everyone knew this was a big round, so we are disappointed, but all we can control is what we can do over the next six days and get to Galway.”
Bristol were overpowered by a physical, unrelenting Bulls team, conceding tries to wing Sergeal Petersen, prop Khutha Mchunu, flanker Elrigh Louw and hooker Jan-Hendrik Wessels, with fly-half Johan Goosen kicking three conversions and a penalty, and centre David Kriel landing one conversion.
Bulls’ bonus-point triumph owed everything to their overwhelming scrummaging superiority, with Bristol restricted to tries from scrum-half Kieran Marmion, wing Ibitoye and number eight Magnus Bradbury, plus one AJ MacGinty conversion.
Bristol were without injured internationals Callum Sheedy, Ellis Genge and Sinckler, while Bulls boss Jake White opted to rest his South Africa World Cup-winning quartet of Willie le Roux, Kurt-Lee Arendse, Canan Moodie and Marco van Staden.
Bulls head coach White admitted that the absence of Sinckler and his fellow England prop Genge from Bristol’s line-up was something his team looked to exploit.
“To be fair, we did say before the game that without Ellis Genge and Kyle Sinckler it was an area we were going to target, so to get a return like that at scrum time is obviously very pleasing,” White said.
“The old adage of forwards winning the game and the backs determining by how much is exactly what happened today.
“I think it is the biggest win the Bulls have had in Champions Cup rugby. I am really happy with our all-round performance.
“Our destiny is in our hands now. We have got Bordeaux at home now, and if we win that then we definitely finish in the top two in the group.
“Away wins are premium. Not many away sides win in any competition, never mind the Champions Cup. An away win and a bonus point is something we will enjoy.”