Nadal lost the first set in a tie-break and looked set to follow defending champion David Ferrer out of the tournament, who lost earlier in the day to Ukraine’s Ilya Marchenko, ranked number 94 in the world.
But the 14-times Grand Slam winner rallied after a difficult start to take the match 6-7, 6-3, 6-1.
”In the second and third sets, I played well, little mistakes and I was very positive,” said Nadal.
He added: ”I think I changed a little bit at the beginning of the second (set).
”I played with a little bit higher intensity and being a little bit more aggressive, going a little bit more for the shots.
”When I was able to make that happen, everything changed, no?”
The powerful Carreno Busta squandered three set points in the first, before finally winning the tie-break 7-5.
The world number 67 stretched his opponent at times and it looked as if Nadal, who won last week in Abu Dhabi, might exit the competition in the first round as he did last year.
But he recovered to give himself a second-round match against the ”dangerous” Robin Haase in the second round on Wednesday.
– Ferrer crashes out –
There was no such luck for Ferrer, who like Nadal the previous year, crashed out at the first hurdle while defending his title.
Ferrer, this year’s number four seed, struggled throughout, losing his serve in the very first game, hitting 43 unforced errors and eventually going down 7-6, 3-6, 2-6 in an eventful clash lasting over two and a quarter hours.
”He was better than me all the match. From the first set, he deserved to win the match,” said a gracious Ferrer, the world number seven.
The Spaniard, who said he lacked energy throughout the match, was playing with a new racquet but said this was not the reason for his loss.
”I am happy with the racquet. The problem is not the racquet, it’s my serve.”
For Marchenko, the result represented the best victory of his career.
Before Tuesday’s game he had never beaten anyone in the top 10.
”It was a fantastic day for me, I am really happy with the performance,” said the 28-year-old.
”It’s a fantastic way to start the season.”
Marchenko even missed a chance to take the first set after squandering a set point serving while 5-4 ahead.
This allowed Ferrer to claw his way back in typical fashion, eventually taking the tie-break 10-8 in an opening set lasting one hour and eight minutes.
But any thoughts that Marchenko might fold were immediately dismissed when the Ukrainian broke the Spaniard’s serve at the first attempt in the second set. The 28-year-old held onto his lead and then powered through the final set to claim a famous victory.
Despite double-faulting three times in the final game, Marchenko eventually closed the match out to claim a second-round clash on Wednesday against Russia’s Teymuraz Gabashvili.
Earlier on Tuesday, Tomas Berdych, the number three seed and last year’s beaten finalist, beat another Ukrainian, Sergiy Stakhovsky, in straight sets, 7-5, 6-4.
The Czech said he was ”feeling good” after his victory. (AFP)