Results from Day 8 of the Australian Open Grand Slam tennis tournament on Monday: Men's singles 4th rd Daniil Medvedev (RUS x4) bt Mackenzie McDonald (USA) 6-4, 6-2, 6-3 Women's singles 4th rd Jennifer Brady (USA x22) bt Donna Vekic (CRO x28) 6-1, 7-5 Jessica Pegula (USA) bt Elina Svitolina (UKR x5) 6-4, 3-6, 6-3 afp