the last 16.
The world number two is in the bottom half of the men's draw which has seen seven-time champion Roger Federer, reigning French Open champion Rafael Nadal, dangerous sixth seed Jo-Wilfried Tsonga and 10th seed Marin Cilic all depart.
As a result, 15th seeded Nicolas Almagro is Murray's closest rival in ranking terms, but the Spaniard has never got beyond the third round at the All England Club.
Murray's opponent Robredo has also never managed to reach the second week.
"Everybody was so obsessed with how the draw was before the tournament started. Now everybody wants to change their views on it because a few guys have lost," Murray said.
"Upsets happen every single day. You can't take any matches for granted. People want to do that often and just write people through to finals or semifinals or whatever. But it doesn't work that way.
"You need to be ready for every match. That's just the way that sport is."
The bottom half of the women's draw has been similarly devastated after world number two Victoria Azerenka withdrew with a knee injury and world number three, Maria Sharapova, the 2004 champion, slumped to shock defeat against Portuguese qualifier Michelle Larcher De Brito.
The highest-ranked player left in that section is the 2011 champion Petra Kvitova, seeded eighth, who faces Ekaterina Makarova, the Russian 25th seed, for a place in the last 16.
Larcher De Brito faces Italy's Karin Knapp, while former finalist Marion Bartoli, the 15th seeded Frenchwoman, tackles Italy's Camila Giorgi.
Elsewhere on Friday, the tournament plays catch-up after heavy rain prevented eight second round matches from being completed on Thursday.
One of the most intriguing sees unseeded Slovenian Grega Zemlja enjoy a 9-8 final set lead over Bulgarian 29th seed Grigor Dimitrov.
Zemlja needed a doctor on court on Thursday to examine his irregular breathing while Dimitrov, watched from the Court Three stands by girlfriend Sharapova, required treatment on his left ankle after slipping and falling.
Spanish fourth seed David Ferrer will start his second round clash against conpatriot Roberto Bautista Agut as the first match up on Court One.
Britain's only survivor in the women's singles, Laura Robson, opens Centre Court action against Colombian qualifier, Mariana Duque-Marino.