RONNIE Wallwork celebrated penning a new two-year Hawthorns deal in style as his first goal in 19 months sealed a deserved - but ultimately edgy - win.
The ex-Manchester United midfielder, who recently committed his future to the club until 2008, polished off a neat Baggies move to give the hosts a two-goal half-time cushion.
Nathan Ellington had earlier opened his account for the season from the penalty spot as Albion laid siege to the U's goal for almost the entire first half.
But it was a much more even contest after the break, with Geraint Williams' newly-promoted side going close on several occasions before pulling a goal back seven minutes from time through substitute Jamie Guy.
Bryan Robson named an unchanged side for the fourth successive game after Ellington passed a late fitness test on his niggling hamstring injury.
Colchester made two alterations, with new loan signing Chris Barker and Chris lwelumo coming in for George Elokobi (suspension) and Johnnie Jackson (hamstring)
The U's made a flying start to this first-ever league meeting between the two teams when, inside ten seconds, Jamie Cureton latched onto Iwelumo's flick-on and dragged a weak shot across the face of goal.
But Albion soon had the visitors on the back foot as they won five corners in succession.
From Jonathan Greening's first flag-kick, Zoltan Gera's persistence enabled John Hartson to tee up Ellington inside the box - but the Duke dragged his shot wide.
Moments later, Hartson towered at the near post to head another Greening corner goalwards - only to see United central midfielder Kevin Watson brilliantly head the ball off the line.
Greening completely miscued his next flag-kick but it somehow found its way through to Ellington whose first-time 18-yard drive was tipped over by U's keeper Aiden Davison.
But Ellington didn't have to wait too much longer to break the deadlock.
Albion were awarded a tenth-minute penalty when United centre-half Wayne Brown pushed Hartson to the floor on the edge of the penalty area.
Ellington made no mistake, coolly slotting the ball to the left of the pedestrian Davison.
The ex-Wigan striker was on fire and he brilliantly teed up Greening inside the box in the 16th minute.
However, the Albion winger dallied on the ball long enough for Watson to slide in and block his right-footed drive.
Colchester didn't record their next effort on goal until the 19th minute when Wallwork slid in to divert Richard Garcia's drive over from Iwelumo's knock down.
Albion were soon back on the attack and the lively Greening did well to beat keeper Davison to Hartson's flick-on, but the ex-Boro man, at full stretch, was unable to direct his toe-poke goalwards.
The Baggies pressure continued and, in the 26th minute, skipper Curtis Davies saw a near-post shot clip off a U's defender and cannon off the post following great work by Gera down the left.
Moments later, Davison had to pull off a marvellous save to push away Paul Robinson's curling 20-yard free-kick.
Colchester earned some respite in the 35th minute when Iwelumo tried his luck from 20 yards, but the U's striker's low drive was easily gathered by Pascal Zuberbuhler.
Albion finally secured the two-goal cushion their total dominance had deserved four minutes before the break.
After a neat spell of left-wing keep ball, Steve Watson dinked the ball to Wallwork who held off his marker 15 yards out before drilling low past Davison - only his second Baggies goal in more than four years at the club.
But the hosts had a real scare in the final minute of first-half stoppage time.
After Cureton had gone agonisingly close in a goalmouth scramble seconds earlier, the pint-sized striker was just a whisker away with a stunning left-foot curler from 20 yards.
United picked up from where they left off after the break and only a fine near-post block by 'Zubi' denied Garcia's right-foot rocket from Kem Izzet's cross-field pass.
The visitors had certainly started the second-half impressively - but Albion almost made it three in the 55th minute.
Ellington spearheaded a swift Albion breakaway and, after exchanging passes with Hartson, the former Bristol Rovers man saw a vicious left-footed drive brilliantly kept out by Davison's one-handed save.
Gera was less accurate moments later, firing well over from 15 yards following Robinson's deflected left-wing cross.
It proved to be the Hungary star's last contribution as he made way for Darren Carter in the 61st minute.
Albion certainly weren't having it all their own way in the second half and Brown soon had his head in his hands after seeing a near-post effort from Watson's corner hit the post.
United went close again in the 74th minute when only Wallwork's point-blank block diverted Garcia's shot over the bar from Watson's corner.
And Albion were really made to sweat when sub Guy polished off the lively Watson's cross with his first touch seven minutes from time to notch his debut senior goal.
The Baggies had made life difficult for themselves but ran down the clock to secure back-to-back home wins.
ALBION (4-4-2): Zuberbuhler; Watson, C Davies, Perry, Robinson; Gera (Carter 61), Wallwork (Albrechtsen 76), Quashie, Greening; Ellington (Chaplow 64), Hartson. Subs not used: Steele (gk), Inamoto.
COLCHESTER (4-4-2): Davison; Halford, Brown, Richards (Baldwin 82), Barker; Garcia, Izzet (Guy 82), Watson, Duguid; Iwelumo, Cureton. Subs not used: Gerken (gk), White, King.
GOALS: ALBION - Ellington (pen 10), Wallwork (41). COLCHESTER - Guy (83).
BOOKINGS: ALBION - Quashie (foul 35), Hartson (foul 40), Wallwork (unsporting behaviour 68).
REFEREE: P Taylor (Hertfordshire).
ATTENDANCE: 17,509.
ALBION STARMAN: Nigel Quashie.
(PICS BY LAURIE RAMPLING)
