PRAGUE, 27 Aug 2015, (AFP) - The 33-year-old joined playing partner Renato Paratore at the top of the leaderboard with birdies on the tenth, 11th and 12th holes heading for the last.
At the 18th, de la Riva holed his long-range approach at the last to finish the opening day on seven under par 65.
"It is very good to finish with a two on a par four, especially on this 18th hole which is very difficult," said the Spaniard.
"I didn't have to take a putt on the 18th, so it is a very good finish. It is perfection."
Paratore, 18, carded seven birdies on his way to a 65, his best score on the European Tour to date.
The Italian very nearly shot a hole in one at the 16th.
"Today I played really solid from the tee to the green and on the back nine I putted really well," said Paratore.
Matt Fitzpatrick, Sam Hutsby, Pelle Edberg and Thomas Pieters are all a further shot behind.
Selected first round scores in the Czech Masters at the Albatross Golf Resort in Prague on Thursday (GBR/IRL unless stated, par 72):
65 - Eduardo De La Riva (ESP), Renato Paratore (ITA)
66 - Sam Hutsby, Pelle Edberg (SWE), Thomas Pieters (BEL), Matthew Fitzpatrick
67 - Roope Kakko (FIN), Jordi Garcia Pinto (ESP), Kristoffer Broberg (SWE), Scott Jamieson, Thorbjorn Olesen (DEN), Pedro Oriol (ESP), Mark Foster, Michael Hoey
68 - Craig Lee, Daniel Im (USA), Pierre Relecom (BEL), Bernd Ritthammer (GER), Lee Slattery
69 - Damien McGrane, Jason Barnes, Robert Dinwiddie, Joakim Lagergren (SWE), Florian Fritsch (GER), Simon Wakefield, Gary Boyd, Eddie Pepperell, Simon Thornton, Filip Mruzek (CZE), Daniel Brooks, Scott Henry, Chris Paisley, David Drysdale, Jamie McLeary, David Dixon, Florian Praegant (AUT), Chris Doak
70 - John Parry, Peter Whiteford, David Horsey, Rikard Karlberg (SWE), Darren Fichardt (RSA), Graeme Storm, Joel Sjoholm (SWE), Prom Meesawat (THA), Peter Uihlein (USA), Cyril Bouniol (FRA), Richard Finch, Kevin Phelan, Carlos del Moral (ESP), Gregory Bourdy (FRA)