Swansea City manager Garry Monk said he was disappointed with his team's display in the 3-0 defeat against Villarreal in their final pre-season friendly at the Liberty Stadium.
Monk's team was outclassed in their final game before kicking off the new Premier League season at Manchester United on 16 August.
Goals by Ikechukwu, Bruno Soriano and Denis Cheryshev left Monk frustrated.
"We made too many mistakes and our decision making was poor," said Monk.
"But if you're going to make that many mistakes, it's better to do it the week before the start of the League season and hopefully get it all out of the way.
"It showed that if you are off it just a little bit against a top quality side you can get punished.
"So I think that will be a sharpener for us to realise that when you go to Manchester United you won't be able to lose that focus and concentration."
|Swansea's early season Premier League matches|
|Sat, 16 August: Manchester United (away)|
|Sat, 23 August: Burnley (home)|
|Sat, 30 August: West Bromwich Albion (home)|
|Sat, 13 September: Chelsea (away)|
|Sat, 20 September: Southampton (home)|
|Sat, 27 September: Sunderland (away)|
Monk took over at Swansea in February 2013 following the departure of Michael Laudrup.
On the day that defender Chico Flores confirmed his departure for Lekhwiya SC in Qatar where Laudrup is now manager, Monk conceded his team were outclassed by their Spanish visitors.
He said he'd told the players that the stylish performance of Villarreal was an indication of what he was striving to achieve at the Liberty Stadium.
"The way they play and the way they are set up is probably two or three years ahead of us," he added.
"They're a very settled and a very fluid side and I said to the players afterwards that's what we have to aspire to.
"That's what we're trying to do with the work that we're doing and putting in place and we're trying to reach something close to what we saw [from Villareal] today."