World number one Andy Murray said he is 'concerned' following defeat by Borna Coric in last 16 of the Madrid Open, but denied being low on confidence.
Murray was beaten 6-3 6-3 by Coric, ranked 59th in the world, on Thursday.
The Briton has endured a tough season on clay, suffering a shock defeat in the last 16 of the Monte Carlo Masters last month and also losing in the semi-finals of the Barcelona Open.
"I definitely think I need to be concerned about today," Murray said.
"It's not always the worst thing losing a match, but it's sometimes the manner of how you lose the match which can be concerning or disappointing.