The road to a title gets harder for the Sonoma County Sol, who face longtime rival Sacramento on Saturday.

Undefeated and coming off a playoff opening shutout, the Sol will host the Gold with the West Region championship at stake.

The winner advances to the final four of the National Premier Soccer League.

The league is the fourth tier of American professional soccer.

Sacramento went on the road last week in Calabasas and upset FC Hasental in the other regional semifinal.

Both the Sol and Gold are seeking a second NPSL title. Sonoma County won the 2009 national championship. Last season, the Sol lost in the West Region title contest.

The rivals played three matches in the Golden Gate Conference this season. Sonoma County won at home, tied at Sacramento, and won at home again.

That last victory was a convincing 7-4 final that cemented Sonoma County's conference title.

The Sol have not lost in 13 games this season, winning 10 and tying three.

Sacramento's only losses this season are to Sonoma County. Saturday's regional championship is at Rancho Cotate High. Game time is 7 p.m. Tickets are $10 for adults and $5 for children.