Hideki Matsuyama admitted the pressure of being in contention at the US PGA Championship got to him during the third round.
The world number three carded a two-over 73 at Quail Hollow on Saturday, but he is just a shot off the lead.
Matsuyama, 25, said the pressure of sharing the overnight lead may have had an impact as he bids to become the first Japanese player to win a major.
"Probably the pressure had something to do with it, being in the last group of a major tournament," he said through a translator.
"But I haven't been spot on all week. And the worries that I had about my swing showed up today in the way I played."
Matsuyama had played down his second round, a brilliant seven-under 64 that saw him surge into contention.
But he ended up hitting just eight fairways in his third round, making it a challenging day.
"I'm disappointed the way I played today," Matsuyama said.
"However, I'm happy to just to be one stroke back and still have a chance and looking forward to tomorrow."
Matsuyama is tied for second with Chris Stroud (71) as the duo chase Kevin Kisner (72).
Stroud, who only made the field thanks to his first PGA Tour win at the Barracuda Championship last week, is upbeat heading into the final round.
"In college, my nickname was Mr. Positivity. It carried on playing golf," he said.
"It definitely helped me early on in my career, just overcoming some very difficult situations: Getting through first and second stage of Q-School, getting on Tour in 2007.
"Been out here, I think this is my 11th season. To finally get a win is really magical. I'm still on cloud nine. I'm just enjoying it."
|Atletico Madrid confirm Costa hamstring injury|
|Thisara stars as Sri Lanka stay alive in tri-nation series|
|Atalanta 0 Napoli 1: Mertens ends drought to keep visitors top|
|Nadal through to meet Cilic as Dimitrov downs Kyrgios|
|Dimitrov holds off Kyrgios as wait for home champion goes on|
|Alexis Sanchez boards plane ahead of reported Man United medical|
|Smith not sour over controversial dismissal|
|Buttler the difference for England, says Morgan|
|Hamburg dismiss Gisdol after fourth loss in a row|
|Brilliant Buttler century sets up England series win|
|Melbourne City 5 Adelaide United 0: Budzinksi & Vidosic braces inspire emphatic win|
|Marco Silva sacked by Watford following ´significant deterioration´|
|Nadal promises greater aggression in the last eight|
|Deschamps knows my thoughts - Lucas Hernandez hints at France decision|
|Nadal battles past Schwartzman in Melbourne|
|Wozniacki: I have nothing to lose|
|Impey claims historic Tour Down Under win|
|Rockets end Warriors´ 14-game road winning streak|
|Klopp: Liverpool wouldn´t sell to rivals during season|
|Spence retains IBF welterweight title with TKO of Peterson|
|Wozniacki cruises into Australian Open quarter-finals|
|Giggs keen to help Bale overcome injury woes|
|Harrison key to containing ´monster´ Fournette|
|Klopp in no rush to replace Coutinho|
|Cook leads, Rahm in contention in California|
|Cavaliers booed after abysmal first quarter|
|Titans hire Mike Vrabel as new head coach|
|Brive deny Worcester after stadium swap|
|Malcom dreams of Premier League but remains unsure of future|
|Guardiola sets target of 10 wins to guarantee title|
|Championship Review: Millwall break Leeds hearts in seven-goal stunner as Wolves lose|
|Messi and Pique welcome Coutinho to Barcelona training for first time|
|Thauvin ´very happy´ at Marseille|
|Guardiola salutes ´outstanding´ Manchester City|
|Saracens still not safe, Scarlets battle through|
|Watford still battling relegation from the top half, insists Silva|
|Rondon ´devastated´ after Everton´s McCarthy suffers horror injury|
|Aguero´s perfect hat-trick is Argentine´s 11th for Manchester City|
|Moyes impressed with Hammers display despite being held by Bournemouth|
|Dyche annoyed with Burnley´s ´big six´ results|
|Manchester City 3 Newcastle United 1: Aguero hat-trick sees pacesetters bounce back|
|Everton fans´ frustration understandable, says Allardyce|
|Wenger responds to Dortmund criticism over Aubameyang affair|
|Bordeaux appoint Poyet as new boss|
|Serena Williams: I can´t figure out a stroller!|
|Lee reigns supreme again as Cheetahs crush Southern Kings|
|Mourinho frustrated at United failure to ´kill´ Burnley|
|Simeone reveals Costa knock as Atletico bemoan dropped points|
|Lambert upbeat over Stoke´s quality after debut victory|
|Nothing happening with Aubameyang - Wenger|
|Mourinho, Wenger expect imminent Sanchez deal|
|Everton confirm McCarthy double leg break|
|Valverde talks of ´respect´ for Atletico as Griezmann saga turns again|
|NFL playoffs: Picks, predictions for AFC & NFC Championship Games|
|Rafinha misses Barca training with Inter closing in|
|Neymar misses Lyon clash with thigh injury|
|Atletico Madrid 1 Girona 1: Griezmann substitution costs Simeone|
|´Proudest son´ Sainz congratulates father on Dakar Rally win|
|Everton 1 West Brom 1: McCarthy horror injury overshadows cagey draw|
|Leicester City 2 Watford 0: Vardy & Mahrez decisive as Puel´s men go seventh|
|West Ham 1 Bournemouth 1: Hernandez proves his worth to Hammers|
|Burnley 0 Manchester United 1: Martial keeps up winning run|
|Arsenal 4 Crystal Palace 1: Early blitz means Sanchez is hardly missed|
|Stoke City 2 Huddersfield Town 0: Lambert makes winning start as Potters inch out of bottom three|
|Crisis, what crisis? Conte lambasts Chelsea critics|
|A goal, two assists and an injury - Monreal the Sanchez replacement at Arsenal?|
|Monchi has no interest in weakening Roma squad amid Dzeko reports|
|Hazard delights in Willian and Batshuayi link-up|
|Federer reveals locker-room advice to ´crushed´ Zverev|
|Resurgent McIlroy working on not being ´one-dimensional´|