A fortnight ago Sainz had to miss the Saudi Arabian Grand Prix due to appendicitis, facing a battle to regain fitness for Melbourne's third race of the season.
But while the Spaniard admitted he wasn't physically at 100 percent, that didn't stop him from qualifying second behind Max Verstappen.
And when Verstappen hit brake trouble from the start of the race, Sainz pounced to break the Dutchman's winning his first win since last year's Singapore Grand Prix, taking a 1-2 for Ferrari ahead of Charles Leclerc.
"I felt really good out there," Sainz said. "Of course a bit stiff and especially physically it wasn't the easiest, but I was lucky that I was more or less on my own and I could manage my pace, manage the tyres, manage everything, it wasn't the toughest races of all.
"Very proud of the team, happy to be in a one-two with Charles here. It shows that the hard work pays off. Life sometimes it's crazy.
"What happened at the beginning of the year, then the podium in Bahrain, then the appendix, the comeback, the win. It's a rollercoaster, but I loved it. I'm extremely happy."
Sainz was unaware of the extent of Verstappen's brake issues as he passed the Red Bull driver on lap 2.
But he said he felt confident about being able to keep him at bay once he got ahead as Ferrari's race pace already looked promising earlier this weekend.
"I think from lap 2 when I was leading," he said when asked when he thought he could race for victory.
"With the pace I had yesterday, I knew I could get it done, especially in clean air. Obviously, the risk of a safety car and red flag here was always in the back of my mind. But luckily, it was a clean race.
"A pity [for Verstappen] because we would have had, I think, a very good fight for P1 today. But yeah, I'm happy to take the win. He's had plenty of them!"
