A stunning solo striking display from McCormack lit up a gloomy day at The Valley and ensured Leeds returned north with the points.
Chris Powell’s men went into Saturday’s match having not conceded in their previous four matches and will feel their own occasional lapses helped halt the streak.
The Scot hit all four of the Whites’ goals and, while the final one was a sublime piece of skill, the Addicks – who have prided themselves on their defensive resolve over the previous two seasons – will feel the first three could all have been averted.
Not to say that it was a write-off of a day for the home side, who were the better side for at least an hour of the game and who could, and should, have been leading at half-time.
Opportunities were not taken when they came, however, and when chances to build momentum presented themselves – certainly after each of their two equalisers – it quickly vanished.
Cameron Stewart’s thunderbolt volley will be shown on highlight reels for weeks, months and years to come, but more simple opportunities were spurned and Leeds, backed by more than 3,000 vocal fans, benefited from McCormack’s killer touch.
The day started in eerily similar fashion to the last time a club from Yorkshire visited SE7, in August, when heavy rainfall caused delays and eventually an abandonment.
Warning signs early in the day forced a delayed kick-off time of 3.30pm, while the turnstiles were not open to supporters until 2.30pm.
A final inspection passed the pitch to play on at 2.15pm – although with a warning that any further downpours might force an another finish – but thankfully the heavens stayed shut and, despite a less-than-ideal-surface, a good game unfolded.
Powell made one change to the side which beat Birmingham City last weekend with Harriott replacing Bradley Pritchard in an attacking move, while Yann Kermorgant also returned to the bench.
In such conditions tackling is always a more difficult proposition as was evidenced early in the game when Dale Stephens received the ball and Luke Murphy’s attempted harry turned into a sliding challenge from behind.
Harriott showed a glimpse of why Powell had entrusted him with a place back in the starting line-up when he cut in onto his stronger left foot and curled just wide of Paddy Kenny’s goal, but it was the visitors who took the lead.
The Addicks had not conceded in seven hours and 27 minutes of football going into the game and Powell will have been disappointed with the ease in which the Whites ended that proud streak.
A long diagonal ball forward from Tom Lees was flicked on by Dexter Blackstock into the path on McCormark and into the space behind Lawrie Wilson – who had initially been drawn towards the initial pass.
Fresh from scoring two goals at Yeovil Town last weekend, the in-form frontman made no mistake as he collected the ball, with the slight aid of some surface water, and calmly slotted past Hamer, making his 100th Charlton appearance.
The home side roared straight back, however, with the lively Stewart cutting in from the left flank and curling narrowly over the bar in a similar vein to the way his opposite winger had 10 minutes earlier.
Rhoys Wiggins, on the side of the pitch least affected by the elements, had a storming first half and nearly created an own-goal equaliser when his pinged ball across the face of goal was nearly turned past Kenny by central defender Jason Pearce.
Still Charlton looked to carve open the Leeds backline and Dale Stephens did just that in the 23rd minute with an incisive cut-back to Simon Church, who touched the ball and then went down under a challenge from a covering defence. No penalty was given.
Unperturbed, the tireless Wales international was alive to opportunity again before the half-hour, with Wiggins this time supplying the ammunition before Church’s shot hit the outside of Kenny’s post from a tight angle.
Charlton deserved to be level on the balance of play, but it was Leeds who nearly stole a second when the energetic Luke Murphy drifted wide and crossed to the advanced Peltier, who headed wide.
Church went even closer to equalising at the other end when, again, Wiggins put in a pinpoint delivery, which was met sweetly on the half-volley and powered towards goal – but Kelly was equal to it.
Stewart then took matters into his own hands. In style.
Jackson’s free-kick curled to the edge of penalty area where it was headed away into the path of the Hull City loanee, who watched it onto his right foot before volley superbly past Kenny from 25 yards.
Having won the club’s goal of the month in September, it will take something spectacular to stop him claiming November’s crown as well.
It nearly got even better for the home side as Harriott showed a delicious piece of technique to take from the edge of the area with the outside of his left boot, which seemed to be dipping beyond Kenny, but also sailed just over the crossbar.
Charlton went into the break in good spirits, but, as they came back out for the second period with their tails up, they suffered a blow less than two minutes in.
Left-back Danny Pugh continued his run into the penalty area, where he was tracked by Harriott and then bundled over upon receiving the ball, as the Addicks winger got on the wrong side and never recovered.
There was little doubt about the spot-kick, nor the subsequent taking of it as McCormack blasted the ball into the roof of the net.
The talented Charlton academy graduate nearly made amends at the other end of the pitch – but Kenny tipped over his deflected effort from 20 yards as the home side pushed for an equaliser.
Puddles of water in front of the east stand made it difficult for Wiggins to be as impactful in the second period, as the home side kicked towards the vociferous away supporters, and without their best outlet the build-up play was less fluid after the break.
The game was more end-to-end by this point and Rodolph Austin, a committed presence in midfield all afternoon, nearly made it 3-1 when he ran onto McCormack’s cross-field ball before shooting wide.
Dorian Dervite, playing in the absence of the injured Richard Wood, was off balance at a crucial time when Jackson’s corner feel to him at the back post – before Charlton’s skipper showed his own scoring prowess by summoning an equaliser.
The hard work was done by Church though who beat two defenders on the touchline before crossing to the near post where Jackson stole a march on his marker to divert the ball past Kenny.
One again, however, any chance of momentum building was undone by conceding almost immediately.
Once again Charlton failed to deal with a long delivery into their area, Dervite this time finding himself out of position, and the ball was flicked to McCormack who completed his hat-trick in powerful fashion by slamming home a volley.
It proved the killer blow and, from then on, the more Charlton chased the game the less likely they looked to find a leveller.
Marvin Sordell and Bradley Pritchard were thrown on to summon something out of their box of tricks, but Leeds were defending in numbers and chances were few and far between.
Jordan Cousins lashed a long-range effort wide and over the bar, before the result was made certain at the other end.
Wiggins’ foul on Austin presented Leeds with a free-kick 20 yards from goal and McCormack, who had one of those days where missing looked the less likely option, curled home a brilliant free-kick past Hamer.
That Charlton should have had a certain penalty at the other end soon after when Sordell was wrestled to the ground was academic.
The most ruthless of striking displays was too much for them on a day where a failure to be as clinical themselves, especially in the first half, aided their undoing.
Charlton: Hamer; Wilson (Pritchard 86), Wiggins, Morrison, Dervite; Harriott (Kermorgant 67), Cousins, Jackson, Stephens, Stewart (Sordell 86); Church.
Subs (not used): Alnwick, Hughes, Evina, Lennon.
Goals: Stewart 45, Jackson 70.
Bookings: Morrison 33 (foul on Brown) Wiggins 90 (foul on Austin).
Leeds United: Kenny; Peltier, Pugh, Pearce, Wootton (Zaliukas 46, Lees; Brown, Murphy, Austin; Blackstock (Smith 76), McCormack.
Subs (not used): Cairns, Green, Tonge, Thompson, Poleon.
Goals: McCormack 17, 47, 73, 90.
Bookings: Kenny 38 (timewasting), Blackstock 44 (kicking the ball away).
Referee: Mr K Stroud.
Attendance: 17,601 (3,284 Leeds)