Polls opened Sunday in Chile's run-off presidential election between Socialist former president Michelle Bachelet and conservative Evelyn Matthei, an unprecedented race for the top office between two female candidates. Pre-election surveys give Bachelet, who was president 2006-2010, nearly twice as much support among voters than Matthei, an economist and former labor minister. Polls opened at 1100 GMT and are scheduled to close at 2100 GMT.