TOKYO, Jan 28 (Reuters) - Japan's Nikkei average opened a tad lower on Friday, but losses were being trimmed as a weaker yen offset the impact from Standard & Poor's downgrade of Japan's sovereign debt late the previous day.
The yen fell to two-month lows against the euro and two-week troughs versus the dollar on Thursday after Standard & Poor's cut Japan's long-term debt rating by one notch to AA minus, saying the country's government lacked a coherent plan to tackle its mounting debt.
The benchmark Nikkei was nearly flat, down 1.30 points at 10,477.36. The broader Topix fell 0.1 percent to 929.05. (Reporting by Ayai Tomisawa; Editing by Chris Gallagher)