Mark McCall viewed Saracens' 22-12 Aviva Premiership victory over Harlequins as a wake-up call for next weekend's European showdown against Wasps.
The reigning English champions and league leaders ran in three-first-half tries but could only add one Owen Farrell penalty to their score after the interval despite dominating the match.
They face in-form Wasps in Saturday's Champions Cup semi-final at the Madejski Stadium and McCall knows an improved performance will be needed against a team that has rocketed up the Premiership into second place.
"It wasn't about missing out on the bonus point, more about how we played. It was a patchy performance, but it is a kick up the backside for Wasps," director of rugby McCall said.
"This game and last weekend's against Northampton are below the standards we'd expect.
"We weren't good in some areas and were a bit loose. We made inroads into Quins but then threw the ball away. We weren't patient enough.
"Our penalty count was that of a losing team and a third of them came at scrum time, so that is something we'll have to fix for next week.
"We scrummed magnificently against Northampton last weekend and we were the opposite of that in this game.
"It's difficult to ask the players to keep fronting up week on week, but Wasps is a massive game and the players are already talking about it in the changing room."
England wing Chris Ashton lifted his tally since completing a 10-week suspension for making contact with the eye area of Ulster's Luke Marshall to five in three matches with a first-half double.
"Chris is playing out of his skin. He scored twice but is gutted he didn't get a third - he felt could have and should have. He's looking really sharp," McCall said.
The defeat in front of a 80,650 spectators at Wembley has all but ended Harlequins' hopes of securing a play-off place.
"We're disappointed because we set out to win. The penalty count was 18-6 against Saracens, so there's a massive disparity there," Quins director of rugby Conor O'Shea said.
"But Saracens are a good side and they're not top of the table for nothing. Chris Ashton finished brilliantly.
"We know where things have gone awry for us this season, but you couldn't fault the attitude.
"We'll wallow because we set our sights high, but we have a Challenge Cup semi-final and once that's over we'll aim for two wins from the two remaining league matches and a trophy."