LONDON Welsh head coach Justin Burnell said they must learn the lessons of their Adams Park defeat to Wasps and quickly.
The Exiles led 17-10 after 50 minutes of the friendly encounter, only for the home side to take control with four tries as both teams rang the changes.
“It was a massive learning curve,” said Burnell.
“At 65 minutes we were more than in the game. But it was those certain areas at crucial times – there were four line-outs in the green zone that we completely missed and you just can’t do that.
“So we’re disappointed, but I also felt there were a lot of positives in there. The scrum was exceptional.
“We’re very realistic as to what the challenge is going to be.”
Welsh will be better prepared for their second taste of top-flight rugby, having had to fight a legal battle just to be promoted in 2012.
But Burnell knows they must raise their game ahead of their Aviva Premiership opener against Exeter Chiefs at the Kassam Stadium on Sunday, September 7.
He said: “We’ve got three weeks now to build and move forward to the Exeter game.
“We’ll have time this week to review it and put things right.
“Whereas last year you could get away with making five or six mistakes at this level, and against a team like Wasps, you can’t get away with making two mistakes.”
Burnell also praised many of Welsh’s debutants.
He said: “I was really pleased; Tim Molenaar, Dean Schofield, and Olly Barkley’s distribution, and then you’ve still got that magical touch in Nick Scott and Seb Stegmann.
“The front row with Taione Vea and Koree Britton from a scrummaging point of view was very good.”
Latest Sport news
9:40am Monday 3rd August 2015
MICHAEL Appleton declared Oxford United were ready for the competitive football to start after they outplayed Coventry City without getting their rewards in a goalless draw.
9:34am Monday 3rd August 2015
MICKEY Lewis is back in football less than a month after parting company with Oxford United.
9:10am Monday 3rd August 2015
DANNY Hylton’s missed spot-kicki against Coventry City could cost the forward his role as Oxford United’s main penalty taker this season.
10:32am Monday 3rd August 2015
OXFORD United have been handed a bye in the first round of the Johnstone's Paint Trophy.
8:30am Monday 3rd August 2015
ANUPAM Sanklecha took seven wickets as Shipton-under-Wychwood returned to winnings way in Division 2 with a five-wicket victory over Gerrards Cross.
7:30am Monday 3rd August 2015
7:10am Monday 3rd August 2015
OXFORD City were well beaten as they ended pre-season with a 4-1 defeat at Solihull Moors.
6:20am Monday 3rd August 2015
HUGO Darby scored 92 as Oxfordshire hold the upper hand against Cornwall after the first day of their Unicorns Counties Championship clash at Banbury.
6:00am Monday 3rd August 2015
BANBURY lost ground in the Division 1 title race after they were beaten by three wickets at leaders Henley.
4:49pm Saturday 1st August 2015
OXFORD United hit the woodwork three times and missed a penalty as they finished pre-season with a strong display but a goalless draw with Coventry City.