Manchester City manager Manuel Pellegrini accepted his side's defending was not good enough in a 4-2 Premier League defeat at Southampton that dented their Champions League qualification hopes.
City remain four points clear of rivals Manchester United - who have a game in hand - after Sadio Mane ran riot with a brilliant hat-trick at St Mary's Stadium, with Shane Long also on target for the hosts.
Kelechi Iheanacho hit a brace after being selected up front in place of the rested Sergio Aguero, but it was not enough for a much changed City side ahead of their semi-final second leg against Real Madrid.
Pellegrini rued the need to rotate his squad because of that upcoming clash in the Spanish capital, and suggested City would have produced a better display had the scheduling worked in their favour.
"I think I had to select a team thinking about who plays on Wednesday," Pellegrini told Sky Sports.
"Maybe if we play on Saturday we can have different options. We'll analyse after the game [if anyone earned the right to play Wednesday].
"I was disappointed in the way we defended, they were less concentrated and we had a lot of problems.
"In the first half, we had another key chance to score, and I think we started the second half well until the corner - that was a decisive goal. After that, it was very difficult.
"It [the top-four race] is exactly the same - we can depend on what we do in the next two games.
"We are three points behind Arsenal - if we beat them we'll be third, waiting for the last game."
Pellegrini had praise for 19-year-old Iheanacho, who made his claim for a place in City's team for the Madrid game by taking his tally for the season to 13 with a second successive Premier League double.
"It's always important for a player to score goals and I think he was one of the players who had a lot of spirit in the whole game. I'm happy for him," Pellegrini added.