It was a shame that a Rory McIlroy showing described in "masterclass" terms by Jordan Spieth was overshadowed by a rules controversy involving the latter.

In continuing the sense of mutual appreciation at the Abu Dhabi Championship McIlroy described the slow-play warning issued to Spieth as "weird." The world No1 was equally baffled by the incident, which under new European Tour guidelines will cost him €2,500 if repeated over the next three days.

When already being watched by the chief referee, John Paramor, Spieth was reckoned to have taken too long over a putt on the 8th hole, his 17th. Spieth admits a deliberate approach but believed he was perfectly entitled to be so, with no group waiting to play from the 8th fairway. Paramor spoke to Spieth as he walked from the 9th tee.

“It was a bit odd,” said Spieth after signing for a 68. “The guys behind us hadn’t even reached the fairway on a par-five. So it didn’t make any sense to me.

“Rory and Rickie [FOWLER]were very surprised. He [PARAMOR]just came up and said you have got this and I said ‘OK, I’ll just move on with the hole.’ For it to be the last putt when they are 15 minutes behind us and we’re off the hole, it didn’t make any sense to me.

“I believe I was going over the time. I read the putt from behind the hole, looked up and couldn’t even see the group behind us at the tee box. So then I called Michael [Greller, Spieth’s caddie] over and said ‘We’ve got time, let’s try and nail this thing down’ because we had been on the clock for a number of holes.

“I understand that, if you are being timed and you are taking longer than the allotted time, you get a bad time. I understand the rule. But it doesn’t make a whole lot of sense when our group had caught up with the one in front, we were coming off the clock and it had no effect on the round. It’s a bit of a grey area. I didn’t fight it. I was respectful about it.”

The fine, of course, would be loose change to Spieth but he will not want a reputation as a slow player – he was spoken to about the same at last year’s Open, for example – and this would mark an inauspicious debut on the regular European Tour.

McIlroy seemed to believe, as is a legitimate theory, that the tour could be a tad anxious to implement fresh legislation.

The Northern Irishman added: “I was surprised Jordan got a bad time on a putt when the guys behind weren’t even approaching their balls back on the fairway. Sometimes we need to apply some common sense, especially when we are not out of position. It’s not like Jordan is a slow player.”

Paramor later moved to clarify his stance. “Pace of play on the European Tour is measured by whether a group keeps to the starting interval between groups, rather than if they are on the same hole, as it is in America,” he said.

This unseemly business rather deflected from a terrific McIlroy start to the year. His 66 was probably the highest score possible amid such a performance, with opportunities slipping by on his back nine in particular.

“That was the Rory that I have seen win majors,” Spieth said. “It was spectacular. It was a pretty unbelievable round on a very challenging golf course. If he keeps striking it like that, I’m going to have to make up for it somewhere else.

“It is nice, it is always fun to watch somebody stripe it. You see a solid shot before you hit one. Typically I’m the one hitting first, though, because he’s so far ahead of me. It was very impressive today, minus one or two short putts which is mainly just rust. I feel like he’s on his A-game.” Spieth bemoaned “short and crooked” play with his own driver but is still firmly in touch.

Henrik Stenson showed no ill-effects from recent knee surgery in recording a 65.

Arguably the most noteworthy display on day one, though, came from the American amateur Bryson Dechambeau. The 22-year-old from California tests the balance of his golf balls as routine in Epsom salts and, to assist with posture, has a set of irons with all shafts the exact same length. Leaving aside the lack of convention, he can clearly play a bit too.

“I never set goals,” said Dechambeau after a 64. “I’m more of a journeyman; I like focusing on the journey process. As it relates to goals or expectations, I don’t really have any. I’m just focused on playing my best, the next shot and the next day.

“I’m a golfing scientist, in a sense, and I’m trying to analyse and understand each and every aspect of the golf course and the way I played, as well. I’ll analyse today and see what I can do better at tomorrow and we’ll go from there.”

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