The world number 11, ranked second for the ATP 250 hard-court event, raced past the challenge of Lacko 6-3 7-5 to book a last-four clash with Juan Monaco.
Murray took the first three games of the match while only dropping three points and, although Lacko came back, the Scot was able to secure the set.
After winning 58 per cent of the points in the opener Murray turned the screw in the second to take 80 per cent.
Both players were serving well with only a handful of openings to break, and the match had to wait until the 11th game before Murray punished his opponent to progress.
Monaco had an opening-set battle with Richard Gasquet earlier in the day, saving two set points in the opener before sending the third seed out 7-6 (9-7) 6-4.
The world number 97 converted four of his eight break opportunities on the Gasquet serve and finished the match winning 52 per cent of the points.
Santiago Giraldo and Tommy Robredo will contest the second semi-final after victories over Viktor Troicki and Andreas Seppi.
Giraldo, the sixth seed, needed 91 minutes to beat Troicki 7-6 (8-6) 6-3 with the Colombian handling his powerful opponent's serve to convert two breaks.
He sealed his semi-final place after saving two break points and will now face Robredo for the fourth time in his career, looking to add to his two wins.
The Spaniard had the toughest test in the quarter-finals as eighth seed Seppi took the match to a final set before Robredo prevailed 6-4 6-7 (5-7) 6-3.
Having sent down 19 aces in the match, the fourth seed put the disappointment of losing the second set tie-break to book a third semi-final appearance of 2014.