It's a circuit stage which looks likely to be the last road stage which will shake up GC with stage 5's time trial and the flatter final stage.
Ruben Elvira Lobato convincingly leads the GC by 20 seconds.
He has looked the strongest when it comes to the final and he and his Pivovarn Lasko team has defended itself well. You feel that his GC challengers Carlos Alberto Ospina and Luis Felipe Laverde Jimenez will need to snag something from Lobato today if they are going to wrest the Lowveld title off of him.
As we saw yesterday the profile of the climb and the narrowness of the roads lead to splits so positioning will be vital. It also proved a difficult climb to attack on and as such we do not get the usual flood of attacks from the pack early on.
On the first of our six ascents just Daniel Eliad can break clear by half a minute or so.
The young Israeli though is pulled back on the descent Het Nieuwsblad notably doing some of the pulling. The Belgian strongman team with numerous GC threats, but need a good break to take the overall you fancy.
No top riders are dropped on the first circuit, though with Ricardo Serrano and Tomislav Danculovic briefly unhitched riders do need to be careful later on.
On the second climb up the God's Window Het Nieuwsblad play out their plan with 18th on GC at 4.20 Rodolfo Fernandez attacking clear with Canadian champ Charles Dionne.
But once again the break cannot get a sufficient gap to keep clear on the descent, with the pace kept high so that splits in the pack can occur.
Ricardo Serrano again misses out, this time with Wang-yip Tang, typically niave racing from the Hong Kong rider.
Fortunately for this duo we get a big reforming again before we tackle our third ascent. Armavia were one of the teams on the front on the last ascent and like Het Nieuwsblad their plan is clearly to get a break.
It is surprising to see their riders able to push to the front at this stage of the race but sure enough Giorgi Nadiradze attacks clear.
At the first King of the Mountains, Eliad took the 10 points at the top comfortably. He is nowhere on those standings and there were surprisingly no attacks for the minor points from anyone high on the race King of the mountains standings.
This time however following Nadiradze taking the maximum, Jaoa Costa attacks away solo to take second place. Again noone else not even KoM leader Mark McNally bothers to go for the minor points.
Costa cannot quite overhaul McNally today, but can move close if he can take decent points on the next climb. This could be a chance as he forms up with Nadiradze and they forge clear, finally getting us our break of the day.
With 55km to go the duo have four minutes on the pack, which is now steadily losing rider from the repeated God's Window climbs. The highest GC casualty being AMEX number three Anthony Colby who was 17th as of this morning.
Onto the fifth and punultimate ascent of God's Window and Het Nieuwsblad play their second card of the day through 15th on GC at 4.14 Kenny Van der Schueren.
The Belgian forges clear at a good time, if he can get clear then perhaps a stage win and a higher place on GC are in the offing. Metinvest and Pivovarna Lasko though are now in full chase mode.
Costa takes the full points at the top of the climb to move to within three points of Mcnally on the King of the Mountains, but Nadiradze has done well thus far to stick to his wheel.
Van de Schueren cannot quite bridge on the ascent or descent and finds himself a minute down with 25km to go. Impressively though he is two minutes clear of the Pivovarna Lasko led pack of 32 riders.
A quick head count back in the 32 man pack and we see Goran Smelcerovic missing, another mid range GC candidate looking like he will drop down GC, with Colby now minutes back.
So onto the last circuit and clearly the riders are pretty tired after three demandind stages and five hard circuits. It is the time to make your move if you can, those that can are Carlos Alberto Ospina, Alberto Rodriguez Oliver and Ruslan Grychenko.
It's a big move and the lack of response from race leader Lobato and Cativen's Laverde Jimenez is telling as these two teams put their domestiques to the front of the pack.
Feeling as if this is the moment to push on as we approach the last kilometre of this climb Ospina pushed hard in this three man power move.
Indeed they bridge to Van de Scheuren, who has struggled to get up to our leaders Costa and Nadiradze. Grychenko calmly crosses as does Rodriguez Oliver with a bit of a struggle.
This is worrying times for Lobato and his Pivovarna Lasko crew, Ospina is too close on GC to allow this gap and indeed the yellow jersey is now forced into a desperate reargaurd action.
Andrea Masciarelli, Angel Vicioso, Benoît Daeninck, Luis Felipe Laverde Jimenez and Ricardo Serrano look to follow this
So following the crest of this final dramatic God's Window climb we have six leaders with 12.5km to go:
Costa, Nadiradze, Van de Scheuren, Ospina, Grychenko and Rodriguez Oliver.
A minute behind them we have a second group of six.
Serrano, Lobato, Vicioso, Daeninck, Laverde Jimenez and Masciarelli.
45 seconds further back we have a group of eight riders.
Leukemans, Fernendez and Herve Milan and Tang Peter Pancake Tareq Esmaeli Tomislav Danculovic
Though in this group only really Pancake is interested in creating the big pace as all the other have riders ahead. This is bad news though for Herve who looks set to lose his GC place.
Up front Serrano does a good job in pulling the lead six back, but as he does Grychenko attacks again with 5km to go.
It's a decisive move as he pulls some 45 seconds clear, no-one despite brief resistance from Serrano, can live with this acceleration.
As Grychenko passes through with 2km to go he clenches a fist.
Still with a decent time gap he could move up and even challenge GC leader Lobato, who may have thought Ospina was the main threat. His super domestique Serrano works hard to limit the losses.
Ospina is not done trying yet either though and now looks to snatch the second place bonifications as he launches a ferocious kick under the kite.
Lobato now looks to minimise his bonification loss, launching a decent sprint of his own. He has looked vulnerable today but has battled hard.
Nothing he could do about today's stage winner, Ruslan Grychenko has not delivered his teams expectations but produces a fine stage win today.
Ospina will take second 21 seconds behind with Lobato through for third.
It means Lobato will take 16 seconds over Ospina into tomorrow's time trial. Grychenko slots in at 30 seconds, ten seconds ahead of Serrano and Laverde Jimenez. Doeninck is back at just over a minute in 6th.
Herve drops back today, right down to 7th on GC is what will be a slightly disappointing stage for Het Nieuwsblad, they didn't really protect their highest on GC that well here. His group rolls in nearly two minutes back from Grychenko.
So the attritional hilly stages have finished with five riders separated by 40 seconds on GC, it comes down to tomorrows time trial to split them.
