Congo, Jan. 11 -- Congo appeared on the cusp of its first peaceful transfer of power with the surprise victory Thursday of opposition candidate Felix Tshisekedi, despite clear signs that a rival opposition leader actually won in a landslide.

With no major protests in the capital and limited violence elsewhere in the vast Central African country, the population seemed to be choosing stability over credibility, accepting Tshisekedi's win and the end to President Joseph Kabila's long and turbulent rule.

But a court challenge to the results could spin the country into chaos, observers warned.

The influential Catholic Church, which deployed 40,000 observers at all polling stations, said official results did not match its findings, and diplo...