SpainCASTELLON, October 22, 2011 - The 31-year-old, playing on the Club de Campo del Mediterraneo course where he was boys champion at 12, carded a third round 64 to go to 19 under for the tournament.
Having shot 63 on Friday, they are the best back-to-back rounds of the Spaniard's career.
Thailand's Thongchai Jaidee moved into second place with a 66, while third on 10 under is England's Ross McGowan and joint fourth one further back are Scot Richie Ramsay, Englishman Anthony Wall and Spain's Gonzalo Fernandez-Castano.
Garcia started his third round assault with a 15 foot putt for birdie at the seventh and made another for eagle on the next.
He then made four more birdies in a row from the 13th with one more on the last.
"It's well set up, but it's not over. Anybody can shoot a round like I did the last couple of days," said Garcia.
"I will have to be very focused. Everybody is going to to try to attack me and I have to realise that.
"There are still a couple of things I would like to improve, but it's obviously getting better and I have more and more confidence."
On playing at home, he said: "It's just a special feeling. The only other time I get this is in the UK when I play the Ryder Cup or the British Open. The energy of the crowd is just amazing."
Garcia has hinted at a return to title-winning ways in recent times.
He seventh in the US Open in June before losing a five-hole play-off to Pablo Larrazabal at the BMW International Open in Munich.
With a ninth place finish in the British Open and 12th at the US PGA he climbed back into the top 50 and if he wins the title on Sunday it could see him just outside the top 30.
Leading and selected third round scores in the European Tour Castello Masters at the Club de Campo del Mediterraneo, Castellon on Saturday (GBR and IRL unless stated, par 71):
194 - Sergio Garcia (ESP) 67-63-64
202 - Thongchai Jaidee (THA) 67-69-66
203 - Ross McGowan 64-70-69
204 - Anthony Wall 67-68-69, Richie Ramsay 72-64-68, Gonzalo Fdez-Castano (ESP) 69-66-69
205 - Ricardo Gonzalez (ARG) 69-66-70, Alexander Noren (SWE) 69-63-73, Romain Wattel (FRA) 70-69-66, Marcus Fraser (AUS) 70-64-71
206 - Steve Webster 74-66-66, Matt Haines 70-66-70, Richard McEvoy 66-69-71, Marcel Siem (GER) 68-68-70, George Coetzee (RSA) 67-70-69
207 - Thomas Aiken (RSA) 68-69-70, David Drysdale 70-67-70, David Horsey 72-65-70, Lorenzo Gagli (ITA) 70-68-69, Gregory Havret (FRA) 69-70-68
208 - Carlos Del Moral (ESP) 70-66-72, Gary Orr 67-67-74, Hennie Otto (RSA) 72-69-67, Robert Coles 68-73-67, Scott Strange (AUS) 69-68-71, Matteo Manassero (ITA) 69-68-71, Matthew Zions (AUS) 70-71-67, Danny Willett 67-74-67, Peter Lawrie 73-69-66, Brett Rumford (AUS) 70-71-67
209 - Soren Kjeldsen (DEN) 74-67-68, Damien McGrane 69-70-70, Magnus A Carlsson (SWE) 71-70-68, Joost Luiten (NED) 71-68-70, Robert Dinwiddie 72-68-69, Stephen Dodd 74-66-69, Niclas Fasth (SWE) 68-69-72, Thomas Levet (FRA) 71-68-70
Selected:
211 - James Kingston (RSA) 69-71-71, Richard Green (AUS) 70-68-73
212 - Keith Horne (RSA) 71-70-71
214 - Anthony Kang (USA) 70-70-74
215 - Mark Brown (NZL) 69-72-74
WD: 139 Andrew Dodt (AUS) 72-67