Verstappen completed the 2.71-mile (4.36-km) lap at the Circuit Gilles Villeneuve in 1 minute, 11.599 seconds. It was the best time in Friday afternoon's (Saturday NZ time) practice and a full second better than his best lap in the morning, when he was also the fastest.
While Gasly's Toro Rosso team-mate Brendon Hartley ended up 16th, he did record the fastest speed trap result with his Honda power unit propelling him to 328kph.
The young Dutchman Verstappen clocked 1:12.198 seconds.
Speaking to Sky Sports F1, Ricciardo said: "We had the upgrade this weekend and my auto struggled more with the driveability, the calibration. I just couldn't get the rhythm", he said. Mercedes was very quick, but I think we are not too far away.
Fernando Alonso had led the session early on after being the first driver to post a representative time on the hypersoft rubber, but eventually slid to seventh. "So it sets us up to be aggressive in attack, so should hopefully make for some good TV as well". The auto has been working really well and we know in qualifying we are missing top speed.
He has raced in the F2 series the last two seasons and now sits 10th in F2 standings after eight races this year, including a third-place finish at Baku, Azerbaijan.
When asked if it means he can win the race from sixth, he said: "I did it in '14".
There was confusion at the end when model Winnie Harlow was told to wave the chequered flag early, prompting the official race to be ended two laps early - a gut-wrench for Ricciardo who set two fastest laps on the final two laps, meaning his team-mate was awarded the gong. He spent most of the second practice session in the pits waiting for his team to iron out an electrical issue, and managed just 17 laps in the session. Sainz finished behind Stoffel Vandoorne in the standings; the Belgian was the other casualty of the session, breaking his rear suspension after hitting the wall through on the exit of Turn 8. "But we're going to get it later anyway, so that's all good". "Even on the harder tyre, they were still doing pretty good lap times". Sauber's Marcus Ericsson also had a spin that left him facing the wrong way on the track, but he straightened out and resumed. He is hoping to build on last year's appearance at his hometown track, when as a rookie he earned the first points of his Formula One career.