Sierra Leone, who were leading 1-0 but trailing the first round tie 3-2 overall, knew if they scored they would progress on the away-goals rule.

In front of a huge Freetown crowd, Sierra Leone skipper Umaru Bangura stepped up only for Williams to produce a dramatic save.

Earlier in the match, veteran forward Kei Kamara had put Sierra Leone 1-0 ahead in the second leg to give the hosts hope after they had lost the first leg 3-1.

Liberia, under new coach Peter Butler, will now go into the group stages.

Equatorial Guinea also advanced on Sunday, beating South Sudan 1-0 courtesy of an Emilio Nsue goal. The first leg had ended 0-0.

In the earlier matches on Sunday, Tanzania beat Burundi on penalties and Ethiopia were away-goals winners over Lesotho.

A further 10 second legs are scheduled for Tuesday with lowly-ranked Djibouti and Somalia defending one-goal leads as they seek their first overall victories in a World Cup tie.

The 14 teams who advance from this round will enter the group stage, where they will join the 26 top-ranked sides in the 40-team, 10-group second phase.

Five places have been reserved for Africa at the 2022 World Cup in Qatar.