According to LiveScience, in a one-on-one encounter, a Bengal tiger would typically have an advantage over an African lion. Both animals are comparable in size, but while lions typically are used to and experienced in fighting with a pack, tigers are solo animals, giving them an advantage.
The Smithsonian provides a documented example of a tiger and lion encountering each other in a one-on-one fight. In 2011, a tiger killed a lion with a single paw swipe in a fight at the Ankara Zoo in Turkey. The tiger found a gap in the fence and made its way into the lion’s pen. When they fought, the tiger severed the lion’s jugular vein with its first attack.