Laxman's sixth One-day hundred on Wednesday steadied the tourists after Pakistan captain Inzamam-ul Haq won his fifth toss in a row and elected to field in the day-night game.
Pakistan face a target of almost six runs an over under lights at the Gaddafi stadium to break the 2-2 deadlock and gain a psychological edge ahead of the three-Test series starting on Sunday.
The total is identical to what Pakistan made in the fourth One-dayer at the same venue on Sunday which India won with five overs to spare.
Laxman, who managed just 27 runs in three previous innings in the series, struck 11 boundaries before he holed out against off-spinner Shoaib Malik.
India plundered 19 runs in the last two overs due to belligerent batting by tailenders Irfan Pathan (20 off 12 balls) and Laxmipathy Balaji (10 off six).
Mohammad Sami, who claimed 3-63, led a fightback by the Pakistani bowlers, whose five wides and as many no-balls were a vast improvement on the 58 wides and 40 no-balls they conceded in the first four matches.
Lanky seamer Shabbir Ahmed finished with 2-56 while Shoaib Akhtar and Malik claimed one wicket apiece.
Among the 25,000 fans at the overflowing stadium was Pakistan President Pervez Musharraf, who watched the match for an hour alongside Indian industrialist Nusli Wadia, the grandson of Pakistan's founder Mohammad Ali Jinnah.
The Mumbai-based Wadia was a special invitee of the Pakistan Government to the match, part of India's first full tour of the neighbours since 1989.
India lost openers Virender Sehwag and Sachin Tendulkar by the 15th over, at which time India had put 79 runs on the board.
Tendulkar, One-day cricket's most successful batsman, failed to make 50 for the sixth successive time in a major final when he edged Sami to wicketkeeper Moin Khan after making 37.
Indian captain Sourav Ganguly added 92 for the third wicket with Laxman when he was dismissed by Akhtar for 45.
Rahul Dravid fell for four, Yuvraj Singh for 18 and Mohammad Kaif for 16 as the Indian middle-order failed to cash in on Laxman's efforts.