The 26-year-old, who split with coach Ivan Lendl in March after a two-year partnership, slumped to a 6-3 6-2 loss in the third round in Spain.
Some days just now I’m playing well, and then the next day I’m not playing well
Asked if he was missing the leadership provided by Lendl, Murray replied: “Possibly.
“When I stopped working with Ivan, that was always going to be the case for a few weeks.”
“Some days just now I’m playing well, and then the next day I’m not playing well.
“Sometimes in matches I’m playing really well for periods, and then other times not great at all.”
Murray resumes his French Open preparations in Rome next week and said that he hopes to have a new coach “soon”.
MORE: The latest football news
MORE: The latest tennis news
BIOGRAPHY: Daniel Sturridge
BIOGRAPHY: Kepa Arrizabalaga