Harlequins captain Chris Robshaw has described his side's 24-19 triumph over Saracens as a "tremendous step forward".
Robshaw, whose side fell behind in the first half to three Owen Farrell penalties, battled back to retake the lead at the half and held on to win with 13 men in the closing stages.
"It is only four points at the end of the day," he told Sky Sports News. "But it's a massive step in the right direction.
"We've got some massive games coming up, but to come here and do that to Saracens was a tremendous step forward.
"We know a lot of people have spoken about if can we match other defences and that kind of stuff, but I think we showed that we can."
Quins are now six points clear at the top of the Aviva Premiership.