Ander Herrera was delighted with Manchester United's second-half performance in Saturday's 2-1 win at Bournemouth but conceded Jose Mourinho's men are making life difficult for themselves.
United have endured a poor start to the season and they were outplayed in the first half, fortunate to reach half-time all square after Anthony Martial cancelled out Callum Wilson's opener.
But the visitors were vastly improved after the break, with Herrera influential, and fellow substitute Marcus Rashford's scrappy stoppage-time strike stole the three points.
"I think we were much better in the second half. They were better in the first," Herrera told BT Sport.
"We cannot give the first 25 minutes away. It makes our games more difficult. How we played in the second half was fantastic, but we want to be a 'whole game' team.
"I think we have to speak about it in the dressing room, we have to improve the first 20, 25 minutes. Against Everton we were good, but we need to be a team who performs well in the whole game."
And Rashford pinpointed the same deficiencies, adding: "We have to improve on starting the games. We usually end them so well. It's a small thing but we need to get it right.
"The important thing is the three points. We've had an inconsistent start to the season and every point is huge for us. It always helps getting a win to prepare for the next game.
"We have a big week ahead [against Juventus and Manchester City] and we need to start the games right."
