Starting on the back nine after fog delayed the start by more than two hours, Foster birdied four consecutive holes and then a further two as he raced into the lead.
Bogies on the fourth and the seventh saw the Englishman sacrifice top spot, only for a birdie on the eighth to see him open up a one shot lead over Ignacio Garrido.
“Obviously being seven under I felt like I could have been a couple better and all of a sudden, going back to 5 you don’t think you're going any good and you're still five under par starting the tournament, which is in a great position to be in.”
The Spaniard made six birdies and, despite a bogey on the third, ended the first round five under par.
On the course that will host the 2014 Ryder Cup, Irishman Peter Lawrie shared the lead after his first nine holes consisted of four birdies, but a bogey on the third saw him card a four under par 68.
Thomas Nørret suffered an inconsistent start but threw himself back into contention after birdies on the last two holes gave him a 69.
Former Ryder Cup captain Colin Montgomerie is three under after just two holes, while England’s Chris Wood countered a seven on the four par 14th to shoot six birdies and move to three under par alongside fellow countryman Robert Coles.
Denmark’s Jeppe Huldahl birdied the 11th, 16th and 18th but bogies on the 12th and fourth saw him make 70 and stay level with Wade Ormsby, from Australia, on two under par.
After a bogey in his first nine holes, Francesco Molinari had thrown himself back into the mix with two birdies and an eagle but a bogey on the seventh saw him slip level on two under par with Miles Tunnicliff, who, after a mixed front nine, helped his cause with a birdie on the 17th.
Matthew Nixon shot 70 and Irish Open champion Simon Dyson made a strong start by birdying the 11th, 13th and 18th, but a six on the fourth par first saw him slip to two under par.
Spain’s Pablo Martin was also two under after birdying the sixth, ninth and 14th. Romain Wattel made an explosive start after five birdies in his first nine holes saw him share the lead for a short time but a bogey on the fourth saw him slip to two under par after 14 holes.
Defending champion Edoardo Molinari, who teed off at 3.40pm, was two under after two holes.
After a mixed opening nine, England’s Richard McEvoy shot three birdies in four holes to move four under, but three consecutive bogies saw him slip to one under after 16 holes.
Nick Dougherty, trying to end his run of 20 successive missed cuts going back to last November, made two early birdies before shooting a seven on the par three sixth, bogies on the eighth and ninth and a six on the four par 12th. An eagle on the last saw him end the day four over par.
