The Swiss Grand Slam record-holder said before the match that often it took him a while to suss out players he had never previously played — and sure enough he ran into trouble against the best player in the Arab world, Malek Jaziri, dropping the first set to loud cheers.
When Federer found a couple of extra gears, taking the next two sets in less than three-quarters of an hour, a 5-7, 6-0, 6-2 win brought him prolonged applause as well.
But the outcome brought a definite sense of premonition with it.
"People might think, okay he's a wild card, so it's an easy draw," the Basel native said before the match.
"I think it's tricky, because I don't know exactly his pattern, his favourite shots, all those things," he said.
"It's always a big match here in the Middle East playing someone like him."
But some of this was dramatically improbable.
The unfamiliar one had not played a match for more than three months because of a knee injury, and was ranked outside the top 100, only getting into the tournament with a wild card.
Still, Jaziri has talent and attitude.
The Tunisian blitzed his first serve at 135 mph, and played with the dangerous freedom of an underdog pleased just to get a bite or two into the big man's trouser-leg.
There were also other pressures on Federer, which he described with a mixture of honesty and a nicely bizarre sense of humour.
"I also think that it played on my mind, you know, that he has this huge knee brace, and a tape, not having played this year," he said, with a crazy chortle.
"Got win — right?"
Federer finished with some great serving statistics, several searing forehands, and a few nimble sideways scrambles that belied his status as the oldest player in the top ten.
He next plays the winner of an all-Spanish tussle between Marcel Granollers and Albert Montanes, ranked 34 and 89 respectively.
His main rival, Novak Djokovic, the world number one who is attempting to win the title back from him, begins on Tuesday against Viktor Troicki, a long-time close friend since the days when they were brought up together in Belgrade.