Lasse Vibe had mixed feelings after Brentford's 4-3 win at Oxford in their third pre-season friendly of the campaign.
The Dane was on the scoresheet in the first half as the Bees took a 2-0 lead following Florian Jozefzoon's opener.
However, Marvin Johnson's penalty and a brace from James Henry saw the west Londoners trail 3-2 before Reece Cole and Sergi Canos both scored to give Brentford the win.
The Bees were brilliant in spells but were also below par at times, which led to the Yellows applying pressure.
And Vibe wants to see more ruthlessness from the squad after the game.
He said: “I thought we looked really good from time to time but also very sloppy in periods which sort of leaves me with a disappointing feeling.
“I think we should be more ruthless. I felt we showed quality out there but we should never let them get the chances they get.
“We gave them the chance to come into our box. It takes away the good stuff we made as well for me personally.”
He carried on: “I agree and I disagree (about our desire to win the game) as I think it shows we didn't take it seriously if I'm honest.
“We can't do that in a competitive game. It was a good exercise and good to get some minutes in. We played on a really good pitch.
“There's lot of positives to take on and negatives to get rid of. It was a game to get out of the system.”