Johnson cards four birdies in a row to share lead at Valero Texas Open

Zach Johnson shot a brilliant second-round 65 to share the lead at the Valero Texas Open.

The two-time champion carded four successive birdies, and six and an eagle in total, in a seven-under-par round which matched Scotland's Martin Laird for the best of the day as he surged to nine under par for the tournament.