Federer hit a dozen aces, kept in 79 per cent of his first serves and won 92 per cent of those points as Lopez – who played his part with some fine serving and volleying of his own – was sent home in just under 90 minutes.
"It was difficult. I've obviously played Feliciano many, many times way back and now on tour as well, but I've never played him when he was ranked so high and potentially so confident," Federer said.
"I just tried to focus on my serve, made sure from that end I wasn't doing any stupid stuff, and at the end I got a bit of a read on his serve.
"Those are the kind of matches you need early on in a tournament to feel good about how you're handling those tough moments."
Following a bright start by Lopez, who was particularly adventurous on second serve, Federer turned the screw with his usual crisp deliveries and some excellent central returns, particularly off the Spaniard’s first serve.
The second seed’s first opportunities to break came at 5-4, but the Swiss spurned three set points in an epic game that Lopez himself looked close to blowing, throwing away five game points of his own.
Federer's next chance was taken rather quickly, however, as he exploited a couple of errors from the world number 15 before catching him short with one of many smart angled second-serve returns, Lopez stumbling into the net to lose the first set 7-5.
The second set started embarrassingly for Federer as an almost hilarious miss drew gasps from the Dubai crowd: he responded with some immaculate serving to hold in a jiffy.
There were no major threats to either server afterwards as the duo showed a masterclass of service play, both men holding to love on occasion and rattling through the games in quick time.
Aat 4-3 to Federer, though, Lopez - who had struggled to deal with balls into the centre of court - imploded: he missed five first-serves and fluffed his lines with two match-losing errors, one wide and one into net to hand the Swiss a vital break.
Federer still had to serve for the match and he did so in style – to love, and with one incredible rally of lobs, drops and volleys to hint at what may come in a possible semi-final against Frenchman Jo-Wilfried Tsonga.
Fourth seed Tsonga moved into the quarter-finals with a straightforward 6-3 6-4 win over unseeded Czech Lukas Rosol.
He will next have to face Juan Martin del Potro after the in-form Argentine swept aside Andrey Golubev 6-4 6-2.