With victory in his second round clash at the Montreal Masters on Thursday, he took his 2017 record to 32-2 - his best start to a season since 2006 when he went 38-2 and finished the year as World No.1.
He also won Wimbledon and Halle on grass.
Former US Open champion del Potro of Argentina snapped an eight-match win streak for Isner, who earned from back-to-back title in July at the Hall of Fame Open in Newport and the Atlanta Open.
In what has already been a magical year for the Swiss Maestro, he will now be pushing for his third title at the Canadian tournament before looking to add a sixth US Open title to his Grand Slam tally, come 28 August in NY.
"Honestly, when I went into surgery, I was rather sad previous year", Federer said. If I felt like I couldn't do all these things, it would not be enjoyable or I wouldn't be doing it any more.More news: Sanchez to miss start of the season
"I think the belief was always there".
Tension was high when Monfils and Nishikori entered a tie-break in the third set. Federer attacked on successive points, angling off a high backhand volley victor, then sealed a love break when Polansky netted his second double fault of the game.
Swiss tennis maestro Roger Federer turned 36 on Tuesday and there was no shortage of gifts or congratulatory messages for the 19-time Grand Slam victor. "I was rather anxious about how I was going to come out of it". Polansky never looked comfortable after he double faulted twice in his first service game and had difficulty handling Federer's pinpoint serves. Losing just one point behind his powerful first serve and two points behind his consistent second delivery, Federer did not face many troubles in the first set. Federer set the tone on serve winning 16 of 19 first-serve points.
Federer will face either American Jack Sock or Spain's David Ferrer in the third round.
Monfils, however, fended off four match points to beat Japanese world number nine Nishikori in a three-set thriller 6-7 (4) 7-5 7-6 (6).
Monfils prevailed 6-7 (4/7), 7-5, 7-6 (8/6) to advance.