This battle took place in Xi’An zoo in China. This lion is 20 – 30 kilograms (44 – 66 pounds) heavier than the tiger according to the zoo keepers of Xi’An zoo.
They are both the same age because they were actually raised together as cubs.
The tiger was originally heavier than the lion because tigers develop faster relative to their age, but this lion has caught up in size after they both reached their prime.
This lion is indeed more muscular than the average African lion in the wild as you can see from the thick and defined thighs but it has deformed hind legs, which negates the advantage that he would’ve gain from his extra weight. The lion started attacking the tiger because the female lions were in heat, therefor the lion was simply treating the male tiger as competition , the same way that he would’ve treat another male lion in this kind of scenario.