Luciano Spalletti admits his choice of starting line-up cost Roma as they lost 1-0 to Villarreal in the second-leg of their Europa League last-32 clash on Thursday night.
A 15th-minute Rafael Borre goal sealed the win on the night for Fran Escriba's side, who ultimately fell well short of progression to the round of 16 after losing the first-leg 4-0.
Speaking after the game, the Giallorossi boss told the club's official website: "I think it's all down to the team I picked. I put [Diego] Perotti and [Stephan] El Shaarawy out wide and they tracked back with the full-backs and ended up getting caught on the defensive line. I caused a few issues because I worked them harder than I planned to yesterday, so I hold my hands up."
When as why Thomas Vermaelen may have had a poor game, he added: "That's also down to me. I put the defence under too much pressure tonight with my team selection and, because of how they play, our opponents were able to receive the ball between the lines. He misplaced a pass and these things happen.
"Of course, mistakes like these can be avoided and he's used to playing on the biggest stage. But yesterday the lads really worked hard in training and so that explains it.
"We always try to boss proceedings, run hard and be aggressive. If, however, you ask certain players to operate in a way that doesn't bring out their style of play, it's anything but easy."
The draw for the round of 16 will be held on 24 February with the first legs played on 9 March, and the second legs on 16 March 2017.
Spalletti concluded: "We want to do our bit. We want to have our say going forward and we have everything it takes to make it into the quarter-finals."
Anderlecht, Genk, Gent, APOEL, Copenhagen, Manchester United, Lyon, Borussia Monchengladbach, Schalke 04, Olympiacos, Ajax, Krasnodar, Rostov, Celta Vigo and Besiktas will all be in the draw along with Roma.