A brief analysis for this case would much appreciated and helpful

Since 1987, A & W has sold a grilled chicken sandwich called a "Chicken Grill." It registered a trademark for that name and product in 1988. Since 2001, McDonald's has sold a grilled chicken sandwich which it calls "Chicken McGrill."A & W alleges that McDonald's has infringed its trademark, used a confusingly similar mark and preyed upon its goodwill in the marketplace. In turn, McDonald's claims that A & W's trademark is invalid because it lacks the essential element of distinctiveness.

Is McDonald's infringing on A & W's trademark? Show your analysis.