Inverness - South Africa's Branden Grace shot a six-under par 66 to remain two shots behind Henrik Stenson after Saturday's third round of the Scottish Open.
Stenson produced a birdie blitz for the second day in a row and will take a two-shot lead going into Sunday's final round.
The former Ryder Cup player, a seven-times winner on the European Tour, followed up his eight-under 64 on Friday with another low-scoring display as a 66 gave him a 16-under aggregate of 200.
American Phil Mickelson, the highest-ranked player in the event, was in a group of four players sharing second place.
The world number eight was slow to get going on Saturday but six birdies in the last 11 holes secured a 66 and put him alongside Grace, Dane Joachim Hansen (69) and Briton John Parry (66) on 202.
"I feel like the game has been sharp and I finally got the score out of it over the last 11 holes," Mickelson said.
The 43-year-old has tended to struggle on links courses this side of the Atlantic and a win would provide a huge confidence boost ahead of next week's British Open at Muirfield.
"It would be a great step in the right direction in my desire to try to capture a first British Open," he said.
Stenson, who won the South African Open title in November, was happy with his performance on Saturday.
"It was probably as good as I've felt all year tee to green," he said.
"That's very promising and I'm pleased with that.
"I'm going to do my best tomorrow.
"It's always a challenge to close out golf tournaments and to win."
Britain's Gareth Maybin stormed up the leaderboard with the best round of the day.
His eight-under 64 included an eagle at the par-five sixth hole, eight birdies and two bogeys.
Maybin, Frenchman Raphael Jacquelin (65) and American Peter Uihlein (70) are on 203.
Overnight leader Chris Doak of Scotland struggled to a 73 for 205.
Leading scores from the third round of the Scottish Open at Castle Stuart (par 72; GBR and IRL unless stated):
200 - Henrik Stenson (SWE) 70-64-66
202 - John Parry 64-72-66, JB Hansen (DEN) 68-65-69, Branden Grace (RSA) 71- 65-66, Phil Mickelson (USA) 66-70-66
203 - Gareth Maybin 69-70-64, Peter Uihlein (USA) 67-66-70, Raphael Jacquelin (FRA) 68-70-65
204 - Simon Khan 65-69-70, Matthew Southgate 69-64-71, Lorenzo Gagli (ITA) 67-67-70
205 - Chris Doak 66-66-73, Paul Casey 70-67-68, Tommy Fleetwood 70-67-68
206 - Ricardo Gonzalez (ARG) 70-68-68, Henni Otto (RSA) 70-70-66, Chris Paisley 70-65-71, Brooks Koepka (USA) 70-68-68, Martin Laird 68-69-69, Eddie Pepperell 69-69-68, Ross Fisher 68-65-73, Nicolas Colsaerts (BEL) 70-68-68
Stenson produced a birdie blitz for the second day in a row and will take a two-shot lead going into Sunday's final round.
The former Ryder Cup player, a seven-times winner on the European Tour, followed up his eight-under 64 on Friday with another low-scoring display as a 66 gave him a 16-under aggregate of 200.
American Phil Mickelson, the highest-ranked player in the event, was in a group of four players sharing second place.
The world number eight was slow to get going on Saturday but six birdies in the last 11 holes secured a 66 and put him alongside Grace, Dane Joachim Hansen (69) and Briton John Parry (66) on 202.
"I feel like the game has been sharp and I finally got the score out of it over the last 11 holes," Mickelson said.
The 43-year-old has tended to struggle on links courses this side of the Atlantic and a win would provide a huge confidence boost ahead of next week's British Open at Muirfield.
"It would be a great step in the right direction in my desire to try to capture a first British Open," he said.
Stenson, who won the South African Open title in November, was happy with his performance on Saturday.
"It was probably as good as I've felt all year tee to green," he said.
"That's very promising and I'm pleased with that.
"I'm going to do my best tomorrow.
"It's always a challenge to close out golf tournaments and to win."
Britain's Gareth Maybin stormed up the leaderboard with the best round of the day.
His eight-under 64 included an eagle at the par-five sixth hole, eight birdies and two bogeys.
Maybin, Frenchman Raphael Jacquelin (65) and American Peter Uihlein (70) are on 203.
Overnight leader Chris Doak of Scotland struggled to a 73 for 205.
Leading scores from the third round of the Scottish Open at Castle Stuart (par 72; GBR and IRL unless stated):
200 - Henrik Stenson (SWE) 70-64-66
202 - John Parry 64-72-66, JB Hansen (DEN) 68-65-69, Branden Grace (RSA) 71- 65-66, Phil Mickelson (USA) 66-70-66
203 - Gareth Maybin 69-70-64, Peter Uihlein (USA) 67-66-70, Raphael Jacquelin (FRA) 68-70-65
204 - Simon Khan 65-69-70, Matthew Southgate 69-64-71, Lorenzo Gagli (ITA) 67-67-70
205 - Chris Doak 66-66-73, Paul Casey 70-67-68, Tommy Fleetwood 70-67-68
206 - Ricardo Gonzalez (ARG) 70-68-68, Henni Otto (RSA) 70-70-66, Chris Paisley 70-65-71, Brooks Koepka (USA) 70-68-68, Martin Laird 68-69-69, Eddie Pepperell 69-69-68, Ross Fisher 68-65-73, Nicolas Colsaerts (BEL) 70-68-68