* Bogey-free final round for champion Porteous
* Trio seal Open berths at Royal Troon (Adds details)
JOHANNESBURG, Jan 17 (Reuters) - South African Haydn Porteous held his nerve for a bogey-free round of 69 to claim a maiden European Tour victory at the Joburg Open on Sunday.
Joint overnight leader Porteous made just five bogeys all week and hit every green in regulation at the Royal Johannesburg and Kensington Golf Club during his final round, while the chasing pack behind him struggled for the same consistency.
The 21-year-old finished the tournament on 18-under-par, two shots ahead of compatriot Zandersaf Lombard (71).
A further shot back was group of four players, all of who looked as though they may steal the limelight on Sunday before fading -- Swede Bjorn Akesson (68), England's Anthony Wall (72), Daniel Im (70) from the U.S. and home hope Justin Walters (69).
The three top-ranked players have also earned their place at he 145th British Open at Royal Troon in July -- Porteous, Lombard and Wall, who qualifies ahead of the other players on 15-under-par by virtue of his world ranking.
Porteous, who missed the cut at last weekend's South African Open after struggling with his game, said he played low-risk golf to keep himself ahead of the field.
"Words can't describe how I feel, it's surreal to be honest," he said at the trophy presentation.
"I've been battling with my golf over the last few months and a lot of sweat and tears have brought me here."
His accuracy off the tee was vastly improved and a feature of his solid final round.
"I had been battling for my driver for the past few days, but I started to hit a few more fairways today and a lot more greens to give myself a chance to make some birdies.
"Unfortunately the putts didn't go in but I was keeping the pressure low and making sure I still made par." (Reporting by Nick Said; editing by Martyn Herman and Pritha Sarkar)