John Garner's novel Grendel is a text which shows the other side of the Anglo-Saxon epic of Beowulf. In the epic tale, Grendel's point of view is never given (in Beowulf, the text is told by an uninvolved and removed narrator (third person)). Grendel is never given a voice. Garner's novel does just this--gives Grendel a voice. Therefore, the tale that Grendel tells is very different from the one which is meant to illuminate the epic hero.
In Garner's text, Grendel does not believe that the fight between himself and Beowulf is a fair one. Instead, Grendel believes that Beowulf's victory over him is the sole result of an accident. Given all of the blood on the floor of Heorot, Grendel slips and Beowulf is able to take advantage of his misstep. Therefore, it is not that Beowulf is actually stronger than Grendel; instead, Grendel's loss to Beowulf was only a slip on his part.