Top seed Fabio Fognini had been due to take on Pablo Cuevas and Tommy Robredo should have been up against Marin Cilic, but the weather put paid to Saturday's schedule.
The quartet will return on Sunday, weather permitting, to play their semi-final in the morning before the winners return for a final in the afternoon at the ATP 250 clay-court event.
Fognini is attempting to go one better than last year, when he was a beaten by Robredo in the final.