The Dubai club, the league champions as recently as 2009, announced late on Monday the shock acquisition of Ricardo Quaresma on an 18-month contract.
Quaresma agreed to join Ahli last Friday having spent five days in the emirate, and has replaced Achille Emana, the Cameroon midfielder, as one of the four foreign players employed at the Rashid Stadium.
"It is a sign of our ambition," said Ahmed Khalifa, the Ahli chief executive.
"It's very rare to find a player of his quality at this time of year and the negotiations were therefore kept very secret. There were a lot of eyes on Ricardo, a lot of people looking to gain his services, but in the end we were able to sign him.
"We have a very good scouting network and [the chairman] Abdullah Saeed Al Naboodah has excellent connections with agents all over the world, so we're always positioned to find the best players available."
Quaresma, 29, was a free agent having last month been released by Besiktas, a side in Turkey's top division.
Despite a nomadic recent existence and questionable temperament, Quaresma represents a major coup for the Pro League and will form one of the country's most exciting attacking line-ups alongside his new teammates Grafite, the prolific Brazilian, and Luis Jimenez, the talented Chilean playmaker.
Khalifa said Quaresma was convinced to join the club by the presence of Quique Sanchez Flores, the Ahli coach who has experience of managing in Spain's Primera Liga, and by the opportunity to sample life in Dubai.
Given his impressive CV, Khalifa is sure Quaresma will have no problem adapting to football in the Emirates, and confirmed the player will make his debut against Al Ain, the champions, when the league resumes on January 21.
His next top-flight test will come four days later at Al Jazira, the Abu Dhabi club currently sitting second in the table, one place above Ahli.
"It's two big matches, and a nice introduction," Khalifa said.
"He's played for Inter Milan, Barcelona, Chelsea and was successful in Porto, too. So a player with this experience won't find any problems settling in the UAE.
"He asked about the league through his agent and players who are already here, so has enough of an idea. He's a smart guy and knows what he's doing.
Khalifa said the reaction to the signing proves Ahli were right to pursue Quaresma, and said: "Bringing such a big name will benefit the football industry here.
"At 29, he's a good age, at his peak and will bring some beautiful individual skills, which is sure to attract more fans.
"For example, when we announced the deal [on Monday night], social media such as Twitter and Facebook looked like it was going to explode. Everybody was shocked and excited. Only [Lionel] Messi winning the Ballon d'Or could knock Quaresma off the top of the most searched sports news here."
Khalifa thanked Emana for his contribution to Ahli last season, too, and revealed the club have already received inquiries about the 30 year old from various Pro League sides.
The possibility exists of a loan deal both inside and outside the UAE, given that only this summer Emana signed a three-year contract.
However, Quaresma's arrival - the player will be introduced this afternoon to the media and to supporters - does not necessarily mark the conclusion of Ahli's transfer activity this month.
"We're always looking at deals that will add value, whether it be signing new players internationally or locally," Khalifa said. "We may have just brought Quaresma, but we won't stop signing simply because of that.
"We're still doing well in the league and have a big chance to climb the championship, and have an opportunity in the President's Cup.
"We have a great chance of trophies this season and want to keep that going."