Leeds have won their opening two matches in the middle-eights and are on a run of seven wins from their last eight games.
That is a huge improvement from the first half of the year, when they lost 16 out of 19, but Garbutt reckons they need to go up a gear today.
“I thought we were a bit off last week against Hull KR,” the front-rower admitted. “There were some times when we didn’t play very well.
“We dropped a few balls and stuff like that so there are things we need to improve on.
“But we are winning games. We have won some tight games, which we weren’t doing at the beginning of the year. At the start of the year, we lost four or five games by six points or less and we seem to be winning those games at the moment. I think we are going all right, without setting the world on fire.”
London were runners-up in the Kingstone Press Championship and thrashed Batley Bulldogs 76-16 in the Qualifiers last week.
“They’re are a good team,” Garbutt said.
“We are under no illusions, we know we are in for a good test.”
Today’s hosts play on a synthetic surface at Ealing Trailfinders, which will add to the challenge for Leeds.
Rhinos were hammered 56-12 on Widnes Vikings’ artificial pitch six months ago, when three players suffered long-term ankle injuries and Garbutt described that as a “dark day”.
He said: “It’s different, we aren’t used to it, but we have got a 3g pitch at Kirkstall so there’s no excuses there.
“We will be looking forward to the challenge.
“We are playing a good side so we are expecting a big game.
“We are taking our best team there and hopefully we will come away with the win, but we know we are going to be tested.”
Today’s game will be Rhinos’ second meeting with a Championship team in the Qualifiers.
They romped to a 62-6 win at Featherstone Rovers two weeks ago, but Garbutt insisted: “We’re not thinking about that at all.
“We have to approach every game the same, whether it’s a Super League team or a Championship team.
“We can’t afford not to do that. I don’t think there’s much in it.
“Leigh are playing really well and London only just lost to Leigh and then did a really good job on Batley.
“On their day they can beat anyone.”
This year has been in sharp contrast to Garbutt’s debut season with Leeds, when he was a Challenge Cup, league leaders’ shield and Grand Final winner in just 14 appearances.
He said: “It hasn’t been the best year, but I am enjoying my footy.
“I think it has been a good year for some young kids who have really stepped forward and I think everyone’s holding themselves in good stead now.”