Careless Hamburg conceded a penalty two minutes from time in a 2-2 draw at Hanover 96, while Bremen squandered a series of chances in a 1-1 draw at home to Borussia Dortmund.
The results left Leverkusen three points clear at the top of the table, with 26 points from 12 matches, thanks to their 4-0 drubbing of Eintracht Frankfurt on Friday.
Bremen are second on 23, ahead of Hamburg on goal difference after a day of missed chances for the chasing pair.
Hamburg came close to an opening goal in a match they dominated when Eljero Elia sprinted down the left wing and curled a shot wide of the far post.
The gifted 22-year-old Dutchman then combined well with Marcell Jansen, sending a quick pass into the box for the German to tap in from close range.
Hanover equalised when Ivory Coast striker Didier Konan snuck in at the near post to head in a corner but Hamburg retook the lead a minute before the break with an Elia header.
The visitors, who also hit the post through Tunay Torun and had several clear chances to seal their win, conceded the costly late penalty for a Tomas Rincon foul on Jiri Stajner, who stepped up to score himself.
"This is a bitter result for us," Hamburg coach Bruno Labbadia, who was sent off for protesting against the penalty decision, told reporters.
"Even more bitter because we were treated unfairly. I told the referee that that decision was based on fear."
BRIGHT START
Bremen, without injured top striker Claudio Pizarro, looked to be cruising to victory against Dortmund when they took the lead in the 36th minute with Aaron Hunt, who days ago won a Germany call-up, crossing for Mesut Ozil to fire home.
The hosts should have grabbed at least one more goal before the break, squandering several chances with Dortmund on the back foot.
The visitors put the ball into the net twice in a minute early in the second half with Lucas Barrios having an effort ruled offside before the Argentine scored his fifth goal in five consecutive Bundesliga matches in the 54th from close range.
Defender Neven Subotic failed to put Dortmund in the lead when he fired over from five metres and Bremen keeper Tim Wiese rescued his team nine minutes from time when he denied Nelson Valdez from close range.
"We had chances early in the second half to make it 2-0," Bremen coach Thomas Schaaf told reporters. "If we had made it 2-0 then it would have probably been enough but even so the result is satisfactory."
