World No 1 Daniil Medvedev is not against the ATP Tour's trial of off-court coaching but the Russian said on Thursday he does not see it having much of an impact.
The trial, which began last month, allows an individual to coach a player both verbally and non-verbally from a designated seat provided that it does not interrupt play or hinder an opponent.
The trial will include the US Open and run through to the season-ending ATP Finals in Turin in November before the ATP evaluates whether to allow it on the Tour in future.
The WTA Tour also has an off-court coaching trial in place.
"During the match, I don't really see how a coach can help," US Open champion Medvedev told reporters. "In some other sports there is tactics, it's so important.
"When a tennis match is there, I guess it can be one match out of five where suddenly he's going to be like, 'change your position on return', or, 'go more to his backhand', if he sees it from the outside."
On Wednesday, American Taylor Fritz said that allowing players to receive instructions during a match was a "dumb rule" that went against the concept of tennis being an individual sport.
Medvedev meets Fritz on Friday for a place in the semi-finals of the Cincinnati Open.
"Let's say I play Fritz tomorrow, it's our first encounter, still I know how he plays and he knows how I play. I don't think on-court coaching tomorrow is going to make a huge difference," said the Russian.
"But in general, I'm OK with it, like I was never against it."
Cameron Norrie cruised into the quarter-finals of the Western and Southern Open with a dominant win over American wild card Ben Shelton.
The British ninth seed was untouchable in the first set, dominating his 229th ranked opponent’s service game to take the set to love.
Although Shelton was able to hold serve twice in the second set, he was ultimately no match for Norrie’s all-around game.
Norrie wrapped up the 6-0, 6-2 result in just 58 minutes to book a clash with Spain’s Carlos Alcaraz.
The 19-year-old eclipsed Marin Cilic in three sets in the third round and could overtake Rafael Nadal and Alexander Zverev for the second spot in the ATP rankings with victory in Cincinnati.
Emma Raducanu’s scintillating early run Cincinnati ended in a 7-5, 6-4 defeat to Jessica Pegula.
The British 10th seed opened her campaign in Cincinnati with impressive victories over WTA Tour veterans Serena Williams and Victoria Azarenka.
But the top-ranked American proved too tough a mountain for the defending US Open champion to climb.
Pegula took control early in the match, dictating ground play and converting two break-point opportunities to clinch the first set.
Another break early in the second then gave world number eight the momentum she needed to secure her place in the quarter-finals.
Pegula’s technical prowess disrupted the clinical tennis Raducanu exhibited in her earlier matches, with the 19-year-old giving up 21 unforced errors in the loss.