Catriona Matthew slipped off the pace during the second round of the ANA Inspiration as Lexi Thompson and Ai Miyazato finished locked together at the top of the leaderboard at the halfway point of the opening major of the season in California.

Matthew, the former Women's British Open champion from North Berwick who was one shot off the lead after round one, had to settle for a level-par 72 for a four-under 140 which left her in a share of 14th, three shots behind the pacesetting duo.

American Thompson joined overnight leader Miyazato on seven-under after firing five birdies, including three in a row on the back nine, in a four-under-par 68 for a 137.

Miyazato did not enjoy such a fruitful second round but her 70 was enough to keep her joint top of the leaderboard with 36-holes to play.

There are six players in the hunting pack a shot back on six-under including world No 1 Lydia Ko and Solheim Cup competitor Suzann Pettersen.

Charley Hull is Britain's leading player on five-under after a tidy round which included two birdies and an eagle.