Last place Rakuten beat the Lions 4-2. The second place Fighters lost to the fourth place Marines 8-4. And the third place Hawks lost to the fifth place Buffaloes 5-2.
The Fighters host the Hawks on 9/26 and 9/27. Those same days, Seibu hosts the fourth place Marines. The Hawks also have a makeup game against Rakuten.
If Seibu wins both of its games (with Daisuke Matsuzaka starting one of them), they will finish first. If the Lions split their games and the Fighters win two, then the Fighters would finish first in the PL for the first time since 1962 when they were called the Toei Flyers. If the Fighters win their three remaining games, and the Lions lose two, then they would finish in first.
In the other league:
The Dragons have 17 games left and the Tigers have 12.