Saracens director of rugby Mark McCall was critical of his side despite the crushing 62-12 Aviva Premiership win over Gloucester at Allianz Park.
Tries from Tom Seabrook and David Halaifonua put the Cherry and Whites in control early on but that was only temporary as the hosts rallied.
Ben Spencer went over for a brace of tries and Sean Maitland, Liam Williams, Juan Figallo, Maro Itoje, Chris Wyles, and Owen Farrell also crossed with the additional award of a penalty try.
McCall said: “We didn’t work hard enough in the first half and they scored two wonderful tries. They were terrible for us though so we spoke at half-time that we needed to take it to a higher level.
“We learnt a good lesson at Leinster in the Champions Cup as it showed you don’t get any second chances and you can’t afford to switch off momentarily.”
Saracens will now face Wasps at home in the semi-final in a fortnight but may be without Schalk Burger and Williams, who both left the field with injuries.
McCall added: “Schalk has a hamstring problem and Liam has a shoulder problem and it’s too early to assess the seriousness.”
Gloucester captain Lewis Ludlow accepted that it had been a difficult afternoon but there were positives to take from a heavy defeat.
He said: “In the first half we showed a lot of promise in attack and we had them in lots of trouble but tries either side of half-time was a double-edged sword and killed us.
“We coughed the ball up in the red zone and you can’t do that against the European Champions and no-one likes a hiding, which we got in the second half.”
Gloucester head coach Johan Ackermann added: “At half-time, I thought the score should have been closer but after the interval, they pinned us down and capitalised on every mistake and had us under pressure in the scrums.
“We focused well for this game but there were two or three crucial penalties, which resulted in a huge momentum swing.”
Next up for Gloucester is the final of the European Challenge Cup against Cardiff next Friday in Bilbao.
Ackermann said: “We need to put in an 80-minute performance but it will be extremely satisfying if we can bring back the trophy and put a smile on our faces.”