Jim Furyk was left baffled after he discovered a unique USGA rule during round one of the US Open.Weather was always going to be a talking point on Thursday of the 126th US Open.The opening round of the US Open was delayed due to fogGettyHalf an hour into the opening round, play was suspended due to fog, leaving the early starters standing in place for 15 minutes.As the weather was not dangerous, and players were entitled to finish that hole if they wanted too, and that’s exactly what the group of Alejandro Tosti, Matthew Jordan and Chase Kyes did.The USA broadcast brought in USGA’s Senior Manager of Rules Jay Roberts to discuss what players can and can’t do during a delay.Roberts was asked if during the delay players were allowed to practice on the previous green while they waited.Roberts said practice, in general, was allowed to continue, both on the putting green and the other practice areas. And they would be allowed to practice on the hole they just completed if they were holding in place on the course, too.Former US Open champion – and the 2027 Ryder Cup captain – was left a little confused by proceedings.“I had no idea,” he said.“It’s something a lot of players don’t know,” Analyst Tom Abbott added.“I was totally unaware,” Furyk responded.As per USGA Rule 5.5b, a player is not allowed to hit a practice stroke between two holes. Furyk was left stunned when Roberts said players were allowed to practice during a non-serious weather delayGettyFuryk is currently suffering with an injury, and has tipped his hat into broadcastingGettyHowever, they can practise putting or chipping on the putting green of the hole just completed, or at any practice green (Rule 13.1e).On top of that, they can also head to the teeing area of the next hole to warm their hands up.The practice strokes must not be made from a bunker, and they should also not lead to an unreasonable delay in play, according to rule 5.6a. There is a reason as to why Furyk may not have known this rule.The USGA rule amounts to a penalty at PGA Tour events, but does not apply during majors.Furyk is a veteran of the PGA circuit and a 17-time winner, including the 2010 FedEx Cup where he claimed $10m in a single day.Furyk is 17-time winner on the PGA Tour and has one major winGettyUltimately, the on-air exchange served as a rare reminder that even golf’s most decorated legends can still learn something new about the rulebook on any given Thursday.Stay up to date with the Golf across all our talkSPORT platforms – subscribe to our YouTube channel for the latest news, opinion, exclusive interviews and our daily unfiltered, unscripted show ‘The S* Word, from 8am ET