Rory McIlroy was tied with rival Patrick Reed for the lead after the delayed conclusion to round one of the Dubai Desert Classic, though the Northern Irishman was not entirely satisfied with his performance.
The build-up to the tournament has been dominated by a spat between world number one McIlroy and LIV Golf defector Reed.
American Reed labelled McIlroy an "immature little child" for blanking him at the practice range and was also alleged to have thrown a tee at McIlroy.
McIlroy said Reed's lawyer served him with court papers on Christmas Eve, although Reed has said he was not behind the subpoena, with the case concerned being one brought by American attorney Larry Klayman relating to divisions between LIV Golf and the PGA Tour.
A strong start from both players on a rain-delayed day one raised the possibility of an intriguing pairing over the weekend.
And the chances of that happening were increased with McIlroy – who started on the back nine – closing birdie, eagle, birdie to finish his first round at six under par.
Reed matched that score thanks to a 15-foot eagle at the last.
Asked for his thoughts about how he played in round one, McIlroy said: "Honestly, not very good. I struggled out there most of yesterday. I thought I did well to be under par by the end of the day. I fought back after some very sloppy rusty golf over the first sort of 14 holes.
"And then today I came out and I don't really know if anything clicked because I don't think I hit enough shots to know, but it was definitely needed.
"I would have been happy with anything around 70 the way I played, and then to come in and shoot 66 is quite the bonus."
The highlight for McIlroy was holing out from 114 yards out of the sand at the eighth (his 17th).
"You know, I wouldn't say I'm the best fairway bunker player in the world. The desert is a little nicer, it's a little more packed down, so you get some better lies," he said.
"All I was thinking about was catching it clean. My tendency out of those lies is to hit it a little bit heavy. As soon as I struck it – went down the grip a little bit just to make sure of the strike – I knew it came out really nicely and it was right down the pin.
"Again, anything inside of 20 feet, I would have been happy with, so that was certainly a bonus."