When Nico Rosberg won the Russian Grand Prix in early May it saw him open up a 43-point lead over Mercedes team-mate Lewis Hamilton.It marked a fourth straight win for the German and seventh in a row overall dating back to last season, as Hamilton's dip in form after wrapping up his third world title continued.
Rosberg's advantage, in the words of Hamilton just this past week, felt like an "impossible mountain to climb".
Yet climb it he did, and in just seven races, completing the job with victory in Sunday's Hungarian Grand Prix.
Here we look at how Hamilton reeled in and overhauled his team-mate at the head of the drivers' standings.
Spanish Grand Prix - 15 MayPole man Hamilton made a decent start to the race but Rosberg enjoyed marginally the better getaway and passed the Briton around the outside into Turn One.
Hamilton was then much faster through the fast Turn Three as a result of Rosberg being in the wrong engine mode and tried to sneak through on the exit of the corner.
Rosberg came across the track to defend his position, forced Hamilton onto the grass where he span into his team-mate and eliminated both on the spot.
Standings: Rosberg 100, Hamilton 57 - gap 43 points.
Monaco Grand Prix - 29 MayAfter dramatically cancelling each other out in Barcelona, Monaco was the scene for Hamilton's fightback to begin in earnest.
Hamilton's first win of the year was helped in part by a slow pit stop for Red Bull's Daniel Ricciardo after a close battle with the Australian, but was nevertheless richly deserved as he embarked on a superb defensive drive over the final 45 laps to keep his rival at bay.
For Rosberg it was an afternoon to forget. He struggled throughout the wet-dry race and could only come home in seventh, ceding 19 points to his title rival in the process.
Standings: Rosberg 106, Hamilton 82 - gap 24 points.
Canadian Grand Prix - 12 JuneAfter waiting six races of 2016 to break his duck, Hamilton won again next time out, edging a strategic battle with Sebastian Vettel's Ferrari.
For the second race in a row Rosberg struggled, coming off worse in a battle with Hamilton into the first corner to slip to ninth. A late slow puncture also affected his race as he came home a deflated fifth.
Standings: Rosberg 116, Hamilton 107 - gap nine points.
European Grand Prix - 19 JuneOne week later and the tables turned again, Rosberg rediscovering his early-season form with a lights-to-flag win at the inaugural race on the streets of Baku in Azerbaijan.
Hamilton started 10th after an "off day" in qualifying and struggled to fifth place in the race, hampered by a problem with an engine setting during the race.
Standings: Rosberg 141, Hamilton 117 - gap 24 points.
Austrian Grand Prix - 3 JulyAnother race enlivened by a collision between the two title rivals.
The squabbling pair were running one-two on the final lap when Hamilton went to pass his team-mate around the outside.
Rosberg turned into the corner late and ran into Hamilton, damaging his own front wing and dropping him to fourth place as the Briton came through unscathed for the win.
Standings: Rosberg 153, Hamilton 142 - gap 11 points.
British Grand Prix - 10 JulyHamilton claimed a fourth Silverstone win after a commanding performance in a wet-dry race.
Rosberg had no answer to his team-mate's pace and fell back into an entertaining scrap with the Red Bull of Max Verstappen.
The Mercedes man emerged victorious from that battle to take second place, but was demoted to third after the race stewards ruled he had benefited from an illegal radio transmission by his team.
Standings: Rosberg: 168, Hamilton 167 - gap one point.
Hungarian Grand Prix - 24 JulyYet again Hamilton had the legs on his team-mate, the Briton controlling the pace from the front after passing pole-sitter Rosberg into the first corner.
Rosberg was allowed to close up behind the leader on more than one occasion, but Hamilton always appeared to have a little more in reserve as he paced his way to the chequered flag.
The result vaulted Hamilton into the title lead for the first time in 2016, but with 10 races remaining don't be surprised to see the order chop and change between now and the final race in Abu Dhabi in November.
Standings: Hamilton 192, Rosberg 186 - gap six points.