Although Ferrari is yet to qualify within two tenths of three-time world champion Max Verstappen this season, the Scuderia had a promising one-two in the Australian Grand Prix, with Sainz leading home team-mate Charles Leclerc and the McLarens.
After both Red Bulls were dominant in the first two rounds, Verstappen was leading the race from pole position in Melbourne when he was struck by braking woes early on and subsequently had to retire, but Sergio Perez wasn't competitive enough to do any better than fifth place.
Sainz is encouraged by Ferrari's performance but warned the Maranello-based squad would struggle to match Red Bull until it brings a big enough upgrade to bridge its rival's advantage.
"Our car worked really well this weekend," the Spaniard said. "But it's going to be tough to keep it up there in every track until we bring an upgrade to close that gap that we saw in Bahrain and Jeddah.
"But around Australia, from lap one, it felt like a race-winning car. And even if Red Bull were also quick and were on pole, that [1min15.915sec pole lap time] in quali wasn't out of reach for us.
"There will be tracks where we are strong like we saw last year. And this year it seems like our race pace is better even on those tracks that we are stronger. And together with a good development programme, I hope that we can challenge Red Bull more often."
A major upgrade has been planned for the Imola round in May with only a small aerodynamic development to be introduced for the next race at Suzuka, but the Scuderia is trying to bring it all sooner, potentially as early as the Japanese Grand Prix.
While it is impossible to know if Ferrari's Australian GP would have panned out the same way had Verstappen not suffered a mechanical issue, its drivers were encouraged by long-run performance in practice.
Sainz even thinks he could have given Verstappen a run for his money after a somewhat promising inaugural lap.
"I felt like I could keep up with him on the first lap and try and take DRS, just to make sure that… DRS around here is super powerful," he added, having completed lap 1 with a nine-tenth gap to the leader.
"Then he lost the car into Turn 3 and there was my chance to get close and attempt an overtake. And then as soon as he was behind, I think he started struggling with the brakes and that was it for him.
"A pity because we would have had, I think, a very good fight for P1 today. But, you know, I'm happy to take the win. He's had plenty of them."
Additional reporting by Franco Nugnes
