Ashwell Prince and Simon Katich both scored centuries for Lancashire as the Division Two leaders' match with Glamorgan heads towards a draw at Old Trafford.
The two former Test players shared 157 runs in 42 overs for the third wicket as Lancashire ended day three on 423-5 in reply to Glamorgan's first innings score of 474.
For South African Prince, who made 113 off just 132 balls, it was his first Championship century of the season, while Australian Katich - who made 115 off 237 - continued the form which saw him score 200 in the second innings against Northamptonshire at Wantage Road last week.
Lancashire, who began day three on 93 without loss, saw their first wicket fall in the eighth over as Karl Brown failed to add to his overnight score of 48 when he dragged a delivery from Graham Wagg on to his stumps.
But it was not before he and Luis Reece had recorded Lancashire's highest opening partnership in the Championship this season by reaching 99.
Reece posted his first half-century for the club but he lasted just eight overs longer than Brown before he was trapped lbw playing back to Dean Cosker for 53.
Prince then made light of a first hour in which just 24 runs were added by scoring at close to a run-a-ball. He lofted Cosker for six in the 53rd over as he motored to his sixth half-century in the Championship this season.
The 36-year-old brought up his three figures in style with a six off Cosker over long-on before, in the 97th over, he tried to sweep Nathan McCullum and gloved the ball to wicketkeeper Mark Wallace.
New Zealand international McCullum, who was only registered by Glamorgan on the morning of the first day, struck again just after tea as Andrea Agathangelou's prod forward was edged to Jim Allenby at slip on 18.
Apart from a sharp chance to Allenby at slip while on 18, Katich was rarely troubled by the Glamorgan attack until just before close when he was caught down the leg side by Wallace off Wagg, who was bowling spin by this time.
Luke Procter, who shared a stand of 90 with Katich, became the fourth Lancashire player to pass 50 on the day as he reached stumps unbeaten on 53.