Both sides were evenly matched at the Borisov Arena, but despite the hosts' swashbuckling attack and resolute defending, they were undone on the stroke of half time.
The Manchester City striker duly controlled and lashed past the Belarusian defenders and into the net to score what would be the winning goal.
The result means that Spain remain on track to qualify in second place with 15 points - three off group leaders Slovakia - while Belarus are all but out in fourth and 11 points off the pace.
Sports Mole analyses the game to see if the reigning European champions were worthy of the win.
On target: 2
On target: 10
Was the result fair?
Based on the match statistics, which heavily favour Spain, it certainly was a fair result and maybe the visitors could have even bagged more goals. In terms of the action on the pitch, however, it was pretty close. Belarus were a handful on the counter, making the most of the gaps left by Spain to get to the final third, and were it not for their toothlessness in attack, we could be talking about a different result. La Roja's defence were well drilled, however, reducing their opponents to a handful of speculative chances, while Iker Casillas was reliable on the few times he was called upon.
They can be proud of their performance against one of the top sides in the world, as they defended stoutly and were not afraid to get stuck in the tackle and, at the other end of the pitch, bomb forward and give their opponents plenty of food for thought. Gorbunov, the goalkeeper whose error of judgement led to Spain's winner, was fantastic throughout the rest of the game, his saves keeping Belarus well in contention until the very end. The gulf in quality between the two sides was probably most evident in attack, as the hosts' attempts to penetrate the Spain back line failed time and time again.
Vicente del Bosque's charges will no doubt be happy with getting all three points and a clean sheet away from home against a well-drilled Belarus side, and the back line certainly did its job, but questions will be asked of the attacking players, who were wasteful at times and should have tested Gorbunov more than they did. That their winner was scored through an opposition mistake rather than through their own good play shows that they were quite lucky to win, but really, all that matters is that Spain navigated a tricky fixture and came out unscathed.
Sports Mole's man of the match
David Silva: The Manchester City man was a constant livewire, carving time and time again through the Belarus defence and taking his chance when it came on the stroke of half time to give his side the win. He also performed admirably in defence and helped keep the host attacks at bay.
In a game where both sides were well drilled and did the basics correctly for the most part, it has to go to Andrey Gorbunov, the Belarus goalkeeper. It's a shame because he was otherwise superb, but his error of judgement, coming out to greet a corner and finding himself stranded amid a mass of bodies, was critical in that it allowed Silva to get what proved to be Spain's winner.
Robert Schorgenhofer's performance on the pitch was relatively anonymous, which is what you want from a referee - it means that they've done their job correctly. His call not to award Spain a penalty in the 26th minute was right, as Maksim Bordachev's challenge on Silva in the box was a ball winner. Meanwhile his booking of Pedro on the hour was also correct, even though a red card, harsh though it may have been, would have been more than justified.
Belarus: Alyaksandr Khatskevich's charges, fourth in the Euro 2016 Group C qualifying table, will travel to Kiev on September 8 to play Ukraine.
Spain: The reigning European champions, second in their group, will host Slovakia on September 5.