Federer hit a running forehand passing shot to break at love and take the set 6-2.
"And this morning, I mean, playing at 1pm is somewhat on the earlier side for me". Pete Sampras' Grand Slam record of 14 titles stood for seven years before it was eclipsed by the current ATP men's singles world number one.
Djokovic took six months off after Wimbledon previous year and returned at January's Australian Open, where he lost in the fourth round. "Back in the day, I used to play six matches in a row". "Nerves were there. I made so many unforced errors".
The 36-year-old had failed to win a Grand Slam title since 2012 when he chose to end his season after Wimbledon in July, 2016, which raised a number of questions about his future in the game.
"We wondered post surgery what it was going to look like, how his elbow was going to react to the strain and stress, but it was his heart and head that didn't react the right way in this match".
"I probably won't play in the very beginning, you know, meaning Monaco".
But Verdasco struck when it mattered, taking a 5-3 lead in the deciding set after breaking the Bulgarian and securing the match on the second match-point.
"I'm just happy that I managed to recover that quickly after surgery and just get out on the court", he added.
His title defence got off to a soggy start on Saturday night when play was suspended because of rain showers with Federer up a set and tied 2-2 in the second.
Israeli Dudi Sela beat British 21st-seeded Briton Kyle Edmund 6-4 6-4 while Luxemburg's 24th seed Giles Muller was upset by Frenchman Pierre-Hugues Herbert 6-3 7-5.
Spanish 11th seed Pablo Carreno Busta defeated Daniil Medvedev 6-1 7-5 but 13th-seeded Roberto Bautista Agut was dismantled 6-1 6-3 by 21-year-old Croatian Borna Coric.