The Dale striker swooped to head home a Dan Moss knockback with eight minutes to play, after the Pilgrims had produced an outstanding rearguard action to keep the table toppers at bay.

United had a glorious chance to equalise immediately after Smith's goal - but home keeper Oliver Whatmuff made a great save to deny Tom Cursons.

Manager Paul Hurst chose to include Marcel Lavinier and Alex Lankshear in his United starting XI, with Matty Carson and Ken Aboh dropping to the bench.

Rochdale enjoyed large swathes of possession and their main source of danger often emanated from overlapping ex-Pilgrim Kyron Gordon.

The clearest chance of the first half fell to another former Pilgrim, in Mani Dieseruvwe, whose glancing header was comfortable for Dan Cameron.

United crafted an opening after the break, with Lavinier brilliantly denied by Callum Perry, before Whatmuff kept out Jordy Hiwula's follow-up.

Moss and Aidan Barlow guided efforts off target - but the former had a hand in Rochdale's breakthrough in the 82nd minute. Moss headed Ian Henderson's deep cross back across goal and SMITH bulleted home a close-range header which had too much power for Cameron.

Whatmuff subsequently excelled to keep out Cursons' effort - as United's equaliser failed to materialise against the impressive title chasers.

Rochdale (3-4-1-2): Oliver Whatmuff; Kyron Gordon, Ethan Ebanks-Landell, Callum Perry; Tarryn Allarakhia (David Tutonda 89), Ryan East (Ed Francis 89), Casey Pettit, Dan Moss; Aidan Barlow (Ian Henderson 80); Mani Dieseruvwe, Devante Rodney (Tyler Smith 63). Subs (not used): Jake Burger, Connor McBride, Bryant Bilongo.

Boston (3-4-1-2): Dan Cameron; Jake Rooney, Jamie Grimes, Connor Teale (Luca Barrington 88); Marcel Lavinier, Jordan Richards, Oisin Gallagher (Greg Sloggett 88), Alex Lankshear; Frankie Maguire; Tom Cursons, Jordy Hiwula (Ken Aboh 59). Subs (not used): Ben Grist, Matty Carson, Arjan Raikhy, Rhys Lovett (gk).

Referee: Zac Kennard-Kettle.

Attendance: 3,296 (246 visitors).

PIC: Chris Bray.