Branden Grace carded a six-under 66 to take a one-shot lead after the opening round of the Texas Open.
The South African, who is without a top-10 finish this year, mixed seven birdies with a bogey in a fine start at the TPC San Antonio on Thursday.
Grace is top of a congested leaderboard, with a group of four players a shot behind him and another 13 at four under.
Americans Will MacKenzie, John Huh and Stewart Cink opened with 67s to be tied for second with New Zealander Steven Alker.
Mackenzie and Huh were runners-up at the PGA Tour event in 2014 and 2012 respectively.
Huh went through bogey-free and MacKenzie's only blemish came at the par-four 10th, while Alker birdied his final three holes.
Among those at four under and tied for sixth is Graeme McDowell, the 2010 U.S. Open champion having holed seven birdies and three bogeys.
Alongside him is Bob Estes, the 51-year-old American whose first of four PGA Tour wins came at the Texas Open in 1994.
Estes, who last won in 2002, made four birdies in a consistent opening round.
Steve Marino, Shawn Stefani, Luke List, Brooks Koepka, Noh Seung-yul, Tom Hoge, Jonathan Randolph, Robby Shelton, Ken Duke, Brian Gay and Bryce Molder are also at four under.
Defending champion Charley Hoffman made a decent start, carding a one-under 71 to be tied for 55th.
|Valverde praises Barca stand-ins after opening win|
|Deportivo La Coruna 0 Real Madrid 3: Bale nets as champions make confident start|
|Dimitrov downs Kyrgios to claim first ATP 1000 crown|
|Celtic star Tierney destined for Premier League, says Adam|
|Deulofeu dedicates Barca win to victims of Las Ramblas attack|
|Guardiola not worried over City´s Everton struggles|
|Inkster revels in USA playing free and loose in Solheim Cup triumph|
|Paris Saint-Germain 6 Toulouse 2: Neymar shines on Parc des Princes debut as Verratti sees red|
|Australia overcome Iran to clinch FIBA Asia Cup|
|Crotone 0 AC Milan 3: Cutrone and Suso star in sizzling start|
|Inter 3 Fiorentina 0: Icardi double condemns Pioli to miserable return|
|Barcelona 2 Real Betis 0: Deulofeu on song as Valverde makes winning start|
|USA hold off Europe to successfully defend Solheim Cup|
|David Luiz and Bakayoko branded ´amazing´ by Conte as Chelsea beat Tottenham|
|Halep steamrollered by Muguruza to miss out on top ranking once more|
|No Wembley worries for Pochettino despite Spurs setback|
|Desire of champions still in Chelsea´s hearts, says Conte|
|Manchester City´s Mendy hails Batshuayi own goal as #bulletheader|
|Chelsea match-winner Alonso hails champion spirit after stunning Spurs|
|Bayern drawn against RB Leipzig in DFB-Pokal|
|Gronkowski delighted after playing first Patriots pre-season game since 2012|
|Big-spending Everton ´expecting to win and win´ - Pickford|
|Welcome to AC Milan - Kalinic´s arrival confirmed|
|Kohli hopes to keep Dhawan in his ´happy zone´|
|Tottenham 1 Chelsea 2: Awesome Alonso ensures more Wembley woe for Spurs|
|West Brom appeal against Robson-Kanu red card|
|Monchi focused on signings not sales at Roma amid Cuadrado links|
|Mo Farah seals 3000m victory in final UK track appearance|
|Injured Cronje replaced by Vermaak in Springboks squad|
|Wagner lauds ´totally important´ Huddersfield wins|
|Lampaert masterfully sprints to victory as Nibali cuts Froome´s advantage|
|Koeman believes Everton can exploit Manchester City defence|
|Electric Dhawan´s ton and Sri Lanka collapse put dominant India ahead|
|Huddersfield determined to make an impact, says Ince|
|Andone comfortable at Deportivo but tempted by Burnley move|
|Former Springbok Spies retires from rugby aged 32|
|Otaegui mounts stunning finish for first European Tour title|
|Fekir: Halfway line wonder goal was about instinct|
|Salihamidzic impressed by Bayern´s new boys|
|Anderson and Broad: England´s deadly duo in Opta numbers|
|Shakespeare expecting Vardy to be fine after knock|
|Bangladesh recall Mominul as Mosaddek replacement|
|Huddersfield Town 1 Newcastle United 0: Fierce Mooy strike sees flying start continue|
|Gullit calls on Conte to apologise to Chelsea exile Costa|
|´Incomprehensible´ Keita is like two players - Heidel|
|Nothing´s off the table - Ward confident he could beat Joshua|
|Kompany ready for next instalment of Rooney rivalry|
|Watzke withering over Barca´s role in Dembele soap opera|
|World number one or 500, it doesn´t matter to Kyrgios|
|Hamburg´s Muller suffers torn ACL celebrating winning goal|
|Iniesta casts doubt on Barca future|
|Hansen, Read and Carter lead tributes after death of All Blacks icon Meads|
|Morata wants to ´make an explosion´ with Chelsea|
|Late May try all but ends Canberra´s Finals hopes|
|I remember one day he started shooting the journalists - Pochettino recalls Maradona mayhem|
|Conte signals intention to remain at Chelsea for ´many years´|
|Norris clinches Fiji International title|
|Indians painting imposing picture as rotation starts to shine|
|MLS Review: Toronto pull clear, Montreal continue run|
|Crawford knocks out Indongo in third round|
|Kyle Busch wins Bass Pro Shops NRA Night Race|
|All Blacks great Meads dies aged 81|
|Judge breaks MLB record for consecutive games with a strikeout|
|Kyrgios edges Ferrer to set up Dimitrov final in Cincinnati|
|Bosz lauds ´special´ Gotze after star´s return|
|Dodgers option Pederson to make room for Granderson|
|USA extend Solheim Cup lead|
|Stenson grabs third-round lead after late birdie barrage|
|Wenger: I´m not thinking about signing players|
|Holder: West Indies were totally outplayed by England|