"Tough battle" refers to a challenging and difficult struggle or fight that requires a strong effort mentally, physically, or emotionally. Full definition
I started my blog during my mom's tough battle with ovarian cancer. (colorandgrace.com)
Your bow can also switch to a shield which is vital in tough battles when the enemy is trying to take you out, though it can only take a few hits. (thevrgrid.com)
«I'm happy for all of the guys on our team because we've been racing our teammates in a very tough battle this year,» said Fellows. (corvetteracing.com)