It hasn't been a great day for the Irish at Day One of the British Open with all four now likely to finish their first rounds over par.

Shane Lowry in the clubhouse at the two-over, Padraig Harrington had a three-over 73 while Darren Clarke shot a five-over 75.

Lowry was disappointed with his round.

"I just scored very badly - 72 is not what you would like out there today.

"It wasn't easy but it wasn't that hard either, it was a bit in between."

"There were some good scores and there were some bad scores as well but the way I played today it should definitely be better than 72."

Rory McIlroy is still on the course but was four over through 12 holes at Royal Birkdale and nine shots off the lead.

Elsewhere, former champion Ernie Els carded his best round at the Open since winning the Claret Jug for a second time in 2012 and the South African admits Royal Birkdale has given him a familiar feeling.

The 47-year-old shot back-to-back 68s over the weekend at Royal Lytham to pip Adam Scott to the title and he posted a similar number at the nearby Southport links.

Despite a bogey at the last Els, who has been troubled by back problems, was happy to finally find some form at the major where he holds the record for sub-70 rounds - extending his own mark to 41.

Two-time major winner Jordan Spieth gave himself nine out of 10 after beginning his bid to secure the third leg of a career grand slam in impressive fashion in the 146th Open Championship.

Spieth carded a bogey-free 65 at Royal Birkdale to share the clubhouse lead with US Open champion Brooks Koepka, whose round included four birdies and an eagle.

As the final groups headed out on to the course, the American pair enjoyed a two-shot lead over compatriot Justin Thomas and the English duo of Ian Poulter and Richard Bland, with Welshman Stuart Manley part of a group on two under on his Open debut.

The 65s of Ryder Cup team-mates Spieth and Koepka equalled the second lowest first round score in an Open at Birkdale, a shot outside Craig Stadler's record of 64 set in 1983.

But after hitting just five of 14 fairways, Spieth knew there was room for improvement as he looks to add the Open title to his Masters and US Open victories in 2015.

London's Alfie Plant shot a one-over-par 71 to sit as the leading amateur after day one of the Open at Royal Birkdale.

The 25-year-old European Amateur champion entertained a sizeable following - all kitted out in #TeamAlfie T-shirts and baseball caps - with a composed round that featured three birdies.

Scotland's Connor Syme was the second-best amateur home after carding 73 while Italian Luca Cianchetti took 75.

The two other amateurs in the field, Southampton's Harry Ellis and American Maverick McNealy, finished seven over and eight over respectively.

Plant's performance, which makes him the leading contender for the silver medal, began with a nerveless birdie at the first and even saw him briefly tie for the lead.

Harrington won his second successive Claret Jug on the Southport links in the event's last appearance at the venue in 2008, finishing with a flourish with a brilliant five-wood to three feet for an eagle at the 71st hole to ensure he won by four strokes.

There was no such magic on his return with a double bogey, one other dropped shot and no birdies in an opening 73 which left him with plenty to do on Friday to remain in the tournament.

"Conditions were tough but they'd set the pins appropriately - it just wasn't a good scoring day for me," the three-time major winner said.

"I was disappointed early in the round not to make more of it.

"I'll be trying my hardest (on Friday) regardless. The key is hopefully I get a bit of momentum in the round but it's not like you can go out and force it."

On the applause he received throughout his opening round, the 45-year-old added: "I seemed to get a lot of that today.

"I enjoyed walking down 17 and 18 so there was a little bit of sentiment in it.

"They can't take it away from me.

"I hit four-wood off the 17th tee, hit the left rough, a great lob wedge out of it and a beautiful pitching wedge straight down the pin which I thought was stone dead. It came up 15 feet short and I left the putt short.

"I'm glad I played it the way I did in 2008."

Update 2pm: Nine years after finishing second in the Open Championship at Royal Birkdale, Ian Poulter made the ideal start in his bid to go one better at the same venue.

Poulter, who had to come through final qualifying to avoid missing a sixth major in succession, carded a three-under-par 67 in testing conditions to overtake Welshman Stuart Manley as the early clubhouse leader.

"It was amazing," Poulter said of his reception on the 18th as he completed his lowest ever opening round in a major at the 54th attempt. "Birkdale nine years ago felt pretty good on Sunday afternoon and it felt just as good today.

"I played really well. I would have taken that before going out. It was raining first thing, the wind was a constant 15 miles per hour and I hit all the shots I wanted to.

"I played careful on a few holes for obvious reasons and committed to a lot of shots. A couple of putts slipped by the edge but it adds up to a decent score so I’m pretty happy."

After playing just 13 tournaments last year due to a foot injury, Poulter had 10 events this season to earn enough FedEx Cup points or money to retain a full PGA Tour card.

He came up short in both categories after missing the cut in the Valero Texas Open in April, but American Brian Gay, who was also playing on a medical exemption after back problems, then alerted officials to a discrepancy in the points structure used for players competing in that category.

Poulter made the most of his reprieve by finishing second in the Players Championship at Sawgrass in his next start, but was unable to convert a share of the 54-hole lead in last week’s Scottish Open after a closing 74.

Heavy rain and wind had made life a misery for the early starters, with former champion Mark O’Meara hitting the opening tee shot at 6:35am straight out of bounds.

O’Meara went on to card a quadruple-bogey eight on his way to an 11-over-par 81, but was far from alone in finding the 448-yard par four a daunting prospect.

One player in each of the first three groups also went out of bounds and the first eight groups were a combined 23 over par for the opening hole before Sweden’s Alex Noren recorded the first birdie.

Playing alongside Poulter, Noren went on to card a 68 which matched the superb effort of Open debutant Manley, who holed a bunker shot for an eagle on the 17th and birdied the last from long range.

"It was very nerve-wracking on the first tee," said the 38-year-old. "I was shaking so I was pretty pleased to make contact.

"But after that I kind of settled my round a little bit, played quite nicely and obviously finished it off in a nice fashion."

With Yorkshireman Matthew Fitzpatrick just one shot behind after a 69 there was plenty for the home crowd to cheer on the opening day, although Americans Jordan Spieth and Brooks Koepka were leading the way on the course.

Two-time major winner Spieth had carded four birdies in his opening 14 holes, while US Open winner Koepka had reached the turn in 33 before carding a hat-trick of birdies from the 11th.