One point splits Lewis Hamilton and Max Verstappen at the top of the drivers' standings following a dramatic Emilia Romagna GP. The third round of the season sees the F1 circus return to Portimao which made its debut in 2020.
Hamilton romped away to victory there last year to win by a comfortable margin, one of his best drives in the sport in recent seasons.
However, Red Bull have provided a significantly stronger threat to Mercedes in 2021 and are set to give the world champions a tough time this weekend.
Why Portimao is so unique
The 4.65km Portimao circuit is very different to Imola and Bahrain which will give us a clearer idea as to the strengths and weaknesses of the Mercedes and Red Bull machines.
It's a low-grip track which punishes the front tyres and the resurfaced asphalt caused big problems up and down the grid last year.
The corners are very long so the drivers will be turning for a long period of time which will really test the front end of the cars.
This is the complete opposite to Bahrain which has shorter radius turns. Many of the bends at Portimao are low-medium speed unlike the high-speed chicanes of Imola.
Warmer conditions are expected this weekend which should prevent the cars from sliding as much as 2020 but the new tarmac will still cause a headache for the teams to find the optimum tyre window.
The hardest Pirelli tyre makes its 2021 debut
The C2, C3 and C4 tyre compounds have been used at the opening two events of 2021 but the Portuguese GP will see the C1 (hardest tyre) make it's first appearance of the season.
Pirelli have also decided to use the C1-C2-C3 tyre selection next week in Spain so it will be fascinating to see whether Mercedes or Red Bull have an advantage on the hardest Pirelli compound.
Red Bull have traditionally struggled to fire-up the harder tyres but their strong qualifying form suggests they have resolved this issue. Pirelli's tyres still have a narrow operating window and Mercedes appear to have slightly better tyre degradation than Red Bull which could be critical.
Hamilton was able to run half of the Bahrain race on one set of tyres and he was reeling in Verstappen towards the opening stint at the Emilia Romagna GP on the intermediate tyres.
Tyre wear was an issue in Portimao last year so Mercedes may have a slight race pace advantage once again.
Red Bull favourites for pole position?
Verstappen took pole position by nearly four tenths of a second at the Bahrain International Circuit and Red Bull should have locked out the front row in Imola if their drivers nailed their Q3 laps.
Hamilton was in a league of his own in Portugal last year, with a bigger advantage to teammate Valtteri Bottas and than normal.
There is nothing to suggest Red Bull cannot start the race from the front. They set the benchmark middle sectors in Sakhir and Imola which feature a lot of twisty corners to test the peak downforce of the cars.
Whilst Portimao will not test the change of direction on the cars, Verstappen and Sergio Perez have to be favourites for qualifying due to the RB16B's prowess in the high-speed turns.
Verstappen was only a quarter of a second behind Hamilton in Portugal qualifying and his Q3 lap was slower than his Q1 attempt, a hint that he did not get the most from his last run in the final part of qualifying.
What can we expect?
It would be a surprise to see either Mercedes or Red Bull romp away. If one of the top two team's does dominate in Portugal, expect it to be Hamilton and Mercedes.
The longer wheelbase cars shine on open circuits such as Silverstone, Spa and Portimao. However, Verstappen will be difficult to beat over one lap so if he is out in front after the first laps, Hamilton could be on the chase just as he was in Bahrain.
Similarly to Imola, you can overtake in Portimao but it's tricky. The only opportunity is down the main straight and it's difficult to defend for the driver ahead as soon as the attacking driver gets alongside going into Turn 1.
Tyres will play a crucial role and Red Bull and Mercedes may have a slightly bigger gap to McLaren, Ferrari and AlphaTauri due to the nature of the track.
It's set to be another tight affair which bodes well for the rest of 2021 as Sakhir, Imola and Portimao are all very different circuits.