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.
The home side threatened on the break but Juve continued to carve out chances with left back Paolo De Ceglie twice going close and Chilean midfielder Arturo Vidal crashing a 25-metre shot against the crossbar three minutes before the break.
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The visitors finally broke through when right-back Lichtsteiner sneaked a header inside the near post after being picked out by Pirlo.
Substitute Luca Marrone fired straight at Consigli after a fine one-two with Matri before setting up Giaccherini to wrap up the points.
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."
At the Stadio Olimpico, captain Totti struck after 34 seconds before volleying his second from an Erik Lamela pass.
Striker Fabio Borini grabbed the third in the ninth minute as Roma went on the rampage.
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.
Roma, who had their previous match against Catania abandoned because of a waterlogged pitch, went 1-0 up when Totti ran on to a cheeky back-flick from Lamela and his fierce shot took a deflection to beat goalkeeper Francesco Antonioli at the near post.
The home team poured forward and quickly doubled the lead with Argentine striker Lamela again finding his skipper and Totti overtaking Swedish striker Gunnar Nordahl who hit 210 goals for AC Milan between 1949-56.
Borini, preferred to Bojan Krkic in attack, th
