Leaders Burton Albion took another sizeable step towards automatic promotion with a crushing 4-0 victory at play-off chasers Port Vale.JJ Hooper spurned a clear chance to give Vale a 19th-minute lead when he fired wide after Michael O'Connor's pass caused confusion in the visitors' defence.But Burton improved as the half wore on and Vale keeper Jak Alnwick made a fine save from Calum Butcher shortly before the visitors took a 34th-minute lead.Vale were short of numbers at the back during a swift Albion counter attack and Lucas Akins slid a low left-foot shot from 15 yards inside Alnwick's left-hand post from Tom Naylor's pass.The goal gave the visitors a boost and they caused further problems for Vale before an own goal by the unfortunate Anthony Grant doubled their lead in first-half stoppage time.Richard Duffy fouled the elusive Stuart Beavon and Mark Duffy's dangerous free-kick looped up off the head of Grant and dropped into the left-hand corner of the stranded Alnwick's net.Burton were in cruise control five minutes after the interval when Mark Duffy cut in from the left and drove an unstoppable left-foot shot from 20 yards just inside Alnwick's right-hand post.And more excellent approach work led to a fourth goal on the hour. Akins pulled the ball back from the left byline and Butcher had plenty of time to take aim and fire a low right-foot shot inside Alnwick's right-hand post from 12 yards.