The Englishman sits on nine-under 201 after another steady round, ahead of Ireland's Shane Lowry who equalled the course record with a seven-under 63 and Darren Clarke, who carded a second successive 70 as he looks for a first win since 2008.
"I was eager to get going and I will be the same again tomorrow. I am ready to go again now if I had to," Wood, who finished in the top five at the British Open in 2008 and 2009, told reporters.
"Tomorrow could be a big day for me but I need to try and treat it like any other round of golf," added the 23-year-old who was tied for second at the Africa Open in January.
A shot further back following a five-birdie 66 is home favorite and twice major winner Jose Maria Olazabal, who had no preparation for the tournament after attending the funeral of golfing great and friend Seve Ballesteros on Wednesday.
"I don't remember putting so well in such a long time - I made 23 putts, there aren't many putt days like today. Tomorrow I will go out there and fight like every day," said the 2012 Ryder Cup captain.
