Former PGA Tour pro Johnson Wagner apologized to the British Open crowd after skulling a shot into the grandstand during a live demo.

PORTRUSH, Northern Ireland — Jacob Skov Olesen is the surprise co-leader of the 153rd British Open at Royal Portrush Golf Club.

The British Open at Royal Portrush started Thursday the way the last one ended: A packed grandstand and throaty cheers for an Irish golfer. Padraig Harrington, a two-time Open champion, hit the opening shot of the 153rd edition of golf's oldest championship with a piercing iron into the wind off the North Atlantic,

The "Golden Bear" and 18-time major winner won the first of his three Opens and completed the first of his three career grand slams along the southeastern Scottish coast in 1966, then called the par-71 layout "the best golf course in Britain."

British Open tickets are available on marketplace sites, including StubHub. However, the only official place to buy tickets for golf's final major is TheOpen.com. Fans can sell their unwanted tickets through the official Resale Platform throughout the tournament.

McIlroy, despite his uneven performances in the P.G.A. Championship and U.S. Open, will be among the favorites this week in his native country, as will Xander Schauffele, the defending champion, and Scottie Scheffler, the top-ranked golfer in the world. Here are five other players to watch.

The simplest one is to wager on the in-form golfers, a list led by Rory McIlroy and Scottie Scheffler. McIlroy may get the nod over Scheffler in some circles this week because he's playing on home soil at Royal Portrush in Northern Ireland.

The crowds following Rory McIlroy for three days at Royal Portrush have been enormous, a reminder of the expectations. On banners and flags and buntings of grandstands there are images of the claret jug,

A half century has passed since Tom Watson captured the first of his five British Opens, defeating Jack Newton by one in an 18-hole playoff at Carnoustie Golf Links in Scotland.