There had been speculation the 33-year-old Pacquiao might consider retirement after losing for a second time in his last three bouts but the Filipino southpaw made it clear he would be back to compete after taking a well-earned break.
"To all my fans, I would like to thank you for your prayers and assure you that I am fine," Pacquiao said in a statement just hours after his stunning defeat in a non-title welterweight bout in front of a sellout crowd at the MGM Grand Garden Arena.
"I am looking forward to a nice rest and then I will be back to fight. On behalf of (his wife) Jinkee and our family we would like to wish everyone a joyous Christmas and a happy and healthy new year."
Pacquiao, who had won twice and drawn once in his three previous meetings with Marquez, was floored by a thunderous right by the counter-punching Mexican with just one second left in the sixth round of a high-energy bout.
The Filipino was also knocked down in the third round but fears of a possible concussion were put to rest after a precautionary CT (computed tomography) scan at nearby University Medical Center hospital after the fight ended.
"The results were negative," said Michael Koncz, Pacquiao's advisor. "We were in and out in just over an hour and Manny was in excellent spirits."
Both fighters had much to prove in their heavily anticipated fourth showdown on Saturday.
Marquez was determined to set the record straight after firmly believing he had been "robbed" by judges' verdicts in their three previous fights while Pacquiao was eager to prove his powers had not diminished with age.
The Filipino had delivered a below-par performance against Marquez 13 months ago when he narrowly retained his WBO welterweight title with a controversial majority decision that was greeted by loud booing from disgruntled Marquez fans.
Pacquiao's preparations for that fight were hampered by various distractions, including marital difficulties, but he has since patched up his relationship with his wife and become a much more disciplined boxer after giving up his former pastimes of cockfighting, gambling and nightclubbing.
In June, however, Pacquiao lost on a hotly disputed split decision to American Timothy Bradley, his first defeat since he was beaten by Erik Morales in Las Vegas in March 2005.
With his ego bruised and his stature diminished, the Filipino set his sights on bold vindication against Marquez, but once again he fell short in his bid.
"I want to congratulate Juan Manuel," said Pacquiao, who slipped to 54-5-2 with 38 knockouts. "I have no excuses. It was a good fight and he deserved the victory. I think boxing fans who watched us were winners too."
Pacquiao's stunning loss has almost certainly written off any chance of a long awaited mega-fight between the Filipino and American Floyd Mayweather Jr., and he is now much more likely to take on Marquez for a fifth time.
"Yes, why not? It's a good fight," said the Filipino, who has won world titles in an unprecedented eight weight divisions. "If you give us a chance, we'll fight again." (Reporting by Mark Lamport-Stokes; Editing by Gene Cherry)