It was Abu Dhabi’s idea, and not a bad one.

Take the tennis-free final weekend of the year and jam into it a three-day, six-player competition grandiosely titled “World Tennis Championship”.

Target the highest-ranked players in the world by offering fat appearance fees for a few days of action in the Gulf sun, with another $250,000 set aside for the winner … and presto! A semi-significant, non-points (exhibition) event to liven up the peak season in the Emirates and give the tennis pros a bit of warm-up action on their way to Australia for the start of the next season.

Having worked in Abu Dhabi for six-plus years, I was around for several editions of this event, about to begin its 10th go-round.

Everything worked like a charm, a time or three. The tournament also has stumbled more than once because of the often-late withdrawal of players pleading illness or injury, requiring organizers to swap in some lesser-known gentleman 10 or 20 ranking places behind the guy who no longer is going to appear.

First, the high points:

The debut event, on the first three days of 2009, featured four of the world’s five highest-ranked players — Rafael Nadal (1), Roger Federer (2), Andy Murray (4) and Nikolay Davydenko (5), plus a couple of still-interesting Yanks, Andy Roddick (8) and James Blake (10).

And it went swimmingly. Everyone showed up, Nadal and Murray reached the final and they fought it out over three sets, with the Briton winning 6-4, 5-7, 6-3.

That wasn’t the only year with lots of top five-or-six  players and perfect attendance. There was the 2011 edition, with Nadal (1), Federer (2), Robin Soderling (5), Tomas Berdych (6), Jo-Wilfried Tsonga (13) and Marcos Baghdatis (20). In the final everyone wanted, Nadal faced Federer and won a taut 7-6, 7-6 match. And in the 2013 edition, the world’s four-highest-ranked players (Nadal, Djokovic, Ferrer, Murray) all showed up and Djokovic defeated Ferrer in the final, 7-5, 6-2.

Good times.

However …

More than once, the declared field has been riddled by absences, with top players dropping out late. And on another occasion, the final wasn’t played at all.

A sort of parlor game among tennis fans in Abu Dhabi is guessing which of the six initially announced (and advertised) players will not show up.

On Christmas Day, 2012, Nadal sent along his regrets (“a stomach virus”), for a tournament beginning two days later, on December 27. Organizers scrambled, even giving Federer a call (no, thanks). Eventually, Nicolas Almagro, then ranked No. 10, agreed to pretty much excuse himself from holiday activities in his native Spain and go straight to the airport. That took the field back up to six, but the tournament was without one of its promoted headliners.

Happily, world No. 1 Novak Djokovic got to the final, though his opponent, the substitute Almagro, was on the other side of the net. To his credit, the Spaniard took the match to three sets before succumbing 6-7, 6-3, 6-4.

Then there was the 2015 tournament, which featured no final at all. It was to have been Djokovic versus the rising Murray, a savory matchup, but the former said, three hours before the match was to begin, that he could not play because of a “high fever”. As it turned out, that final was doomed one way or the other, because Murray was considering pulling out with a sore shoulder. But because Djokovic pulled out first, Murray took the $250,000 winners prize.

And there is the current edition.

First, Stan Wawrinka (No. 9) and Milos Raonic (24) were announced as dropping out, on December 20, because of physical issues. To be replaced by Kevin Anderson (14) and the young (20 years old) Russian Andrey Rublev (39).

And then, today, Nadal, again the world No. 1, dropped out, citing the need for further rest ahead of the 2018 season. The Bat Signal was sent up again by promoters Mubadala, and this time it was answered by Roberto Bautista Agut, a Spaniard ranked No. 20.

Leaving Dominic Thiem of Austria the highest-ranked player in the tournament, at No. 5 — though Djokovic, ranked No. 12 after cutting his 2017 season short, is playing. As of this writing.

The field is not much to look at, in terms of ATP rankings which, to be fair, were thoroughly shaken up this year, as opposed to the previous eight or nine years, which usually featured the Big Four, in some order or other, at the top.

The six players this time around (as of this writing): Thiem (No. 5), Pablo Carreno Busta (10), Djokovic (12), Anderson (14), Bautista Agut (20) and Rublev (39).

No word yet if Bautista Agut will be slotted into Nadal’s semifinal seeding. (Nos 1 and 2 in the tournament go straight to the final four; the other four guys play in the “quarterfinals” on Thursday next.) The other time Nadal dropped out late, Almagro jumped into the semis.

So.

In any given year, the Mubadala World Tennis Championship can look like the final days of a grand slam, in terms of the collisions of greats.

In other years, like this one, it looks like the final days of something far less imposing. Say, the Ecuador Quito Open. At least, the sun usually shines. It’s pretty dependable.