He said: "We have to be very sharp in defence on Friday. Our attacking game is working really well and we're producing good rugby. But we will have to concentrate on our defensive play against London Irish.
"Irish will be a different prospect to Northampton as they will play a lot of rugby and move the ball around.
"They are a danger because they have a lot of individuals who have the ability to beat people one on one. They have players who have a licence to run and pop-up anywhere."
Warriors conceded five tries at Northampton last weekend and Hill says that the same defensive play will not be tolerated in the future.
"We had a big inquest on Monday to find out why we went 37-3 down because that's unacceptable. I think some of the players were in awe of the opposition at the start and we can't afford for that to happen again.
"London Irish will be full of confidence after getting their first win of the season last weekend so we will have to make sure we start well."
The Head Coach also thinks the Friday night atmosphere will be a boost for his side: "The atmosphere at Sixways during Friday night matches is electric so it will be interesting to see how much that helps us," he added.
"It is a big game. We've got Irish and Sale here in our next two Aviva Premiership home games. We know we're performing well and doing the things we should be doing.
"Everything is going the right way and if we win on Friday night I think our season will really kick on."