The phrase "tight race" means that there is a very close competition or contest between two or more competitors, which is difficult to predict. Full definition
But field organizing can make a crucial difference, particularly in tight races. (epolitics.com)
In fact there is just a single point separating the top five teams so it really is shaping up to be an extremely tight race for the title. (justarsenal.com)
Easily my favorite of the three I own and it's a very tight race. (solesociety.com)