The two Spaniards met up in the city and went to a restaurant for a bite to eat.
De Gea is back in Manchester after he left the club when his contract expired at the end of last season.
He was the Red Devils‘ No1 for 12 years.
The 32-year-old, who is still a free agent, returned to England on Monday to attend to his £3.5million mansion in Hale, Cheshire.
He had supposedly spent the summer with his wife Edurne and two-year-old daughter Yanay at their house in Madrid.
De Gea was spotted in the stands cheering on Man Utd’s Women team last night as they drew 1-1 with Paris Saint-Germain at Leigh Sports Village.
And this afternoon he met up with current United star Reguilon, posting a snap of them on his Instagram with the caption: “Good to see you amigo.”
De Gea never played with the left-back at club level but they have crossed paths as part of the Spanish national team.
With goalkeeper Andre Onana under pressure after several high-profile mistakes, some fans are hoping their old stopper returns to Old Trafford.
FREE BETS – BEST BETTING OFFERS AND BONUSES NEW CUSTOMERS
One said: “De Gea’s really wanting that contract.”
Another added: “I hope Reguilon’s begging him to come back.”
A third joked: “He’s in Manchester more now than he was before.”
Reguilon is currently recovering from a muscle injury and reportedly played in a secret friendly against Barnsley yesterday.
As for De Gea, he is allegedly in no rush to find a new team and will wait for the correct opportunity.
MAN UTD NEWS LIVE: Stay up to date with all of the latest transfer and takeover news from Old Trafford