Pulheim, Germany ? Robert Karlsson of Sweden took a one-stroke lead in the Mercedes Benz Championship after shooting a 3-under 69 in the second round on Friday. Karlsson had three birdies on the front nine and finished at 8-under 136. First-round co-leader Jean Francois Lucquin of France was one back after a 71. John Daly was eight shots back after a 71.