The Trotters gave a Premiership debut at right-back to Bolton-born defender Nicky Hunt whilst summer signings Kevin Davies and Stelios Giannakopoulos also played as Wanderers looked to record three successive wins away at Old Trafford.
Wanderers started out pretty even against the arch enemy giving as good as they got for a good hour, but it was the Red Devils who had an early chance when Jussi Jaaskelainen superbly tipped over an effort from Ole Gunnar Solksjaer and within minutes Kevin Nolan had Bolton's first chance when he went down the other end only to see his chip well saved by American goalkeeper Tim Howard who was making his debut in the United goal.
Solksjaer again had a chance to open the scoring but he failed to capitalise on some good work from Ryan Giggs. Kevin Davies then could of opened the scoring for Wanderers on his debut but he couldnt keep his shot down following a good headed lay off by Henrik Pedersen.
United took the lead on 34 minutes. Bruno N'Gotty had upended Ruud Van Nistelrooy on the edge of Wanderers area and Ryan Giggs neatly tucked away the resulting free kick past Jaaskelainen's left post to celebrate the first of two goals for the Welsh international.
Kevin Nolan and Jay Jay Okocha both had half chances for Bolton after the break and Sam Allardyce introduced French World Cup winner Youri Djorkaeff into the fray but it was the introduction of teenager Christiano Ronaldo which stepped Sir Alex Ferguson's team up a level. The 18-year old who became the country's most expensive teenager when signing for United last week from Sporting Lisbon caused the Trotters defence problems and seemed to boost United up as did fellow new boy Eric Djemba-Djemba.
On 70 minutes the home side could have furthered their lead, Kevin Nolan pulled back Ronaldo in the area but Van Nistelrooy's resulting spot kick was excellently saved by Jaaskelainen in the Wanderers goal, which marked a second successive penalty miss by the Dutchman.
However United did get their second two minutes later when Van Nistelrooy's shot was only parried by the Finnish keeper Jaaskelainen in the Bolton goal and an unmarked Giggs was on hand to score his second.
Bolton brought on Delroy Facey and Per Frandsen in the hope to claim something back from the game but the late United surge wasn't something that Big Sam's team could reply to.
On 77 minutes Paul Scholes added a third when he rounded Jaaskelainen in contraversial circumstances as it seemed Van Nistelrooy was in an offside position but the referees assistant let the goal stand. Ricardo Gardner could of reduced the errears on 82 minutes but he saw his header thump the crossbar leaving Howard stranded.
Van Nistelrooy added a fourth with a few minutes remaining to give the Champions a winning start, however Bolton until 70 minutes or so did themselves proud but they need to take more of their chances when they come along and should be hoping that level of performance is improved upon come the visit of Blackburn Rovers to the Reebok Stadium next weekend.