Battle of Corus
The Battle of Corus (281 B.C.) was one of the last battles fought among the Diadochi themselves, although the dynasties that formed would still continue clashing for many years to come.
In the battle Seleucus, aided by Ptolemy Keraunos (the original Diadochi Ptolemy had died in 283) defeated Lysimachus. Seleucus himself killed Lysimachus in hand-to-hand combat. At the time Lysimachus was about 80 years of age, while Seleucus was 77.
Encyclopedia of Military History, Dupuy & Dupuy, 1979