Sainz clinched his third podium of the season finishing third at the Sochi Autodrom on Sunday, having led the early stages of the race before slipping behind Lando Norris.
Sainz looked set to finish fourth before the late downpour pushed him up to third after a well-timed run to intermediates after Lewis Hamilton and Max Verstappen.
Sainz has worked throughout 2021 to try to level up at Ferrari since his change from McLaren, but is now 8.5 points ahead of teammate Charles Leclerc in the standings.
The result closed a solid weekend for Sainz who saw him qualify second on Saturday in wet conditions, prompting the Spaniard to call it the best weekend so far with Ferrari.
“I think I managed to have a very solid weekend in practice, especially in Q3, and then a good start and good pace management in very difficult conditions,” said Sainz.
“I’m not going to lie, I’m proud of the weekend. I think the team also did a very good job with all the pit stops yesterday going on the soft tire at the right time, today taking the intermediates at the right time.
“Overall I think this is my strongest weekend at Ferrari.”
Carlos Sainz Jr., Ferrari SF21, Lance Stroll, Aston Martin AMR21 and Daniel Ricciardo, McLaren MCL35M
Photo by: Mark Sutton / Motorsport Images
Sainz passed Norris on the descent to Turn 2 on the first lap, but was passed just before entering the pits at the end of lap 14 as he struggled with graining in the tires.
At one point Sainz was told he looked set to finish the race in fifth place, which he conceded “was a bit of a surprise” at the time.
“After leading the race you are at least sure that you are in the fight for the podium,” said Sainz.
“I didn’t know exactly where the others were on the track at the time. I knew I had made a pit stop and I knew no one was overcutting me. The pace was therefore correct.
“Maybe our simulations suggested that because everyone was going to put the medium at the end, we would be easy prey for them, and we would most likely end P5.”
After clearing the traffic, Sainz was able to pick up his pace and grab third place thanks to the late rain, although he admitted that the result “is not as good” after leading the race.
“What we have to keep working on as a team is to make sure that the next time I’m in a race leader position, we hold it up and we win the race, we don’t suffer as much as we suffered with the graining and we weren’t that vulnerable on the straights and stuff, ”said Sainz.
“[We need to] make sure we keep improving as a team to keep it going next time.