July 8 (Reuters) - England"s Jack Senior produced a flawless round of seven-under-par 64 to take the opening-round lead ahead of a chasing pack full of big names at the Scottish Open on Thursday. Senior, world number 353, carded seven birdies to sit one shot ahead of American world number three Justin Thomas and Race to Dubai champion Lee Westwood who are honing their games ahead of next week"s British Open. Four of the world"s five top-ranked players were on show in North Berwick but it was Senior who made the most of the perfect scoring conditions. Senior, 32, has two victories to his name on the second-tier European Challenge Tour but only two top-10 finishes in 61 appearances on the European Tour. "I"ve won at every single level I"ve played at," Senior said. "I don"t shy away from the top of the leaderboard and when I"m out in front, I don"t tend to back away. "There"s going to be very little wind over the next three days and you"re going to have to keep hitting good shots and keep rolling the putts in." England"s Westwood feels at home at The Renaissance Club, having been made an honorary member when he lived in Edinburgh a few years ago. "I read the greens pretty well here and that was the kind of day it was out there today," Westwood said. "You"re going to have a lot of chances. You"ve got to make your fair share. "I"m happy with 65, six under par and it"s a good score to build on for the rest of the week." Playing his first round as a major champion after his triumph at the U.S. Open, Jon Rahm made seven birdies and two bogeys in a 66 that left him two strokes off the lead. The Spanish world number one"s score was matched by compatriot Alvaro Quiros, Ryder Cup players Matt Fitzpatrick, Tommy Fleetwood and Ian Poulter, England"s David Horsey, Belgian Thomas Detry, South African George Coetzee and American Ryan Palmer. World number five Xander Schauffele and Europe"s Ryder Cup captain Padraig Harrington were a further stroke back in a group of 14 players.