Quins were undone on Saturday by a second-half flurry from the Exiles, as both Blair Cowan and Alex Lewington crossed for tries in the space of three minutes, despite England scrum-half Danny Care replying for the visitors.
It marked a third defeat in five league games but O’Shea insists his side, who won the title in 2012, can bounce back stronger from their lacklustre start.
“I’ve said to the guys inside we’ll be written off, and yes we probably will, but it’s too early to be doing that,” he said.
“Nothing in life is easy and nothing in life worth getting is easy. But we cannot go out and play with the lack of direction and physicality that is the trademark of our game. This league, and that’s what we’re going to have to get used to, is becoming more and more competitive and anyone can beat anyone on the day.”
For Brian Smith’s London Irish side it was their first home victory of the season and came in fine style.
And the director of rugby insisted that it was pure guts and determination that had made the difference at the Madejski Stadium.
“I just thought it was a really courageous effort. We lost Kieran Low in the first three minutes and we were going up against a team that was going to throw the kitchen sink at us,” Smith said.
“You don’t beat Quins by surprise or by accident so I think the squad deserves it for a lot of effort, courage and fighting spirit.”
Saracens director of rugby Mark McCall, meanwhile, admitted his side were far from perfect as the Aviva Premiership leaders made it five wins from five with a 19-12 victory over London Wasps.
The home side went ahead through Alex Goode’s penalty and a Will Fraser try before Chris Bell touched down for Wasps. Three Owen Farrell kicks reestablished Sarries’ dominance although Wasps secured a losing bonus point when Bell crossed again.
“Sometimes you’ve just got to win and dig in. In the past we’ve been comfortable in a lot of the games and against Wasps we had to do it differently,” McCall said. “I’m delighted we rolled up our sleeves and won comfortably in the end.”
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