In the day's other match, Francesco Totti struck twice to set a league scoring record as resurgent AS Roma climbed to sixth by crushing Cesena 5-1.
"I will play until I'm physically unable to do what I want," the 35-year-old Totti told the Mediaset Premium TV channel.
"If we continue to play like this we'll go far. We're enjoying our football and pleasing fans too," he added after claiming his 211th goal for Roma, a league record for a single club.
In Bergamo, Swiss defender Lichtsteiner nodded in Andrea Pirlo's brilliant pass after 55 minutes to give Juve a deserved lead before substitute Giaccherini's volley made the game safe eight minutes from time.
Juve had early chances to open the scoring with Alessandro Matri blasting Simone Pepe's inviting centre over the bar and Pepe screwing a right-foot effort wide five minutes later.
Defender Andrea Barzagli then struck the post in the 11th minute and Mirko Vucinic's half-volley forced Andrea Consigli into a near-post save.
Juve coach Antonio Conte said the tag of 'winter champions', handed out by the media after the first half of the season, had no value.
"That title means nothing to me... but my boys are overcoming all obstacles. It's been an incredible first half," he told Sky Sports.
"We're top and unbeaten after playing against some teams that started our matches as favourites."
Third from bottom Cesena pulled a goal back through Brazilian Eder after 59 minutes but defender Juan (62) and Miralem Pjanic (70) clinched Roma's fourth straight league win as they chalked up 30 points from 18 games.
