A great cover of the William Devaughn tune,
The Massive Attack bassline has been simplified
compared to the original track which has a lot of improvisation in it.
I recommended you check that version out if you haven't heard it already!
 
Intro

G|----------------------------------------------------------------------|
D|--4-4------4-4------4-4------4---3---2-2------2-2----2----------------|
A|------4--4-----4--4-----4--4---4---4-----2--2------2---2--2--2-3--3-4-|
E|---------------------------------------------------------0------------|

G|----------------------------------------------------------------------|
D|--2-3-4-4------4-4------4-4------4---3---2-2------2-2----2------------|
A|----------4--4-----4--4-----4--4---4---4-----2--2------2--------------|
E|----------------------------------------------------------------------|

                                                     "Though you may not..."

The bass pauses at 0:19's and you hear the first lyric,
The bassline resumes at 0:21's and you basically repeat the riff throughout
remainder of the song.

Main Riff (pretty much the same)
  
G|----------------------------------------------------------------------|
D|--4-4------4-4------4-4------4---3---2-2------2-2----2----------------|
A|------4--4-----4--4-----4--4---4---4-----2--2------2---2--2--2-3--3-4-|
E|---------------------------------------------------------0------------|

G|-----------------------------------------------------------------------|
D|--2-3-4-4------4-4------4-4------4---3---2-2------2-2----2-------------|
A|----------4--4-----4--4-----4--4---4---4-----2--2------2---2---2-3--3-4|
E|-------------------------------------------------------------0---------|

G|----------|
D|--2-3-4-4-|    At this point you return to the start and just play
A|----------|    it over and over!
E|----------|

Enjoy