Friedrich doubled down on Sunday, the final day in Latvia, making it a clean two races from two in the two-man bob.
The reigning Olympic, World, and World Cup champion Friedrich claimed victory over fierce rival Johannes Lochner on Sunday, just as he did on Saturday.
This time pushed by Alexander Schueller, Friedrich clocked 49.61 on Run 1 and 49.53 on Run 2 to total 1:39.14, just 0.21 seconds ahead of Lochner and Eric Franke.
In fact, the top five in Race 2 on Sunday was exactly the same as the first race on Saturday with Switzerland's Michael Vogt/Michel Sandro in third (+0.65), Germans Christoph Hafer/Ammour Issam fourth (+0.73) and Latvian pair Ralfs Berzins/Edgars Nemme fifth (+0.74).
Women's two-man bob Olympic champ Mariama Jamanka also got off to a flying start on Saturday, claiming her sixth career World Cup victory.
Jamanka won with push athlete Vanessa Mark, but Austrians Katrin Beierl and Jennifer Onasanya ran a fine race too, finishing just 0.13sec off the winners.
Germany start strong, Russia thwarted by Covid-19
It was a good weekend for Germany's sliders overall. Kim Kalicki and Anabel Galander were third in the two-woman bob, just 0.58 off the pace of compatriots Jamanka and Mark.
Galander celebrated a podium finish on her World Cup debut, and we didn't see Stephanie Schneider, reigning World Cup champion, who was not selected for this event by Germany.
There was good news for Swiss pair Melanie Hasler and Jasmin Naef who placed fourth, 0.96 behind, their best World Cup result to date.
And a new track start record of 5.21 seconds promised much for Germany's third pair of Laura Nolte and Deborah Levi until an unfortunate crash on their first run put an end to their challenge.
The Russian team did not compete after a number of members of the team tested positive for Covid-19, meaning they took no part in the bobsleigh contests in Sigulda.
Sigulda Skeleton: Dukurs delights home fans
He may be 37 but Latvian slider Martins Dukurs shows no signs of slowing down.
In the absence of Olympic champion Sungbin Yun, the two-time Olympic silver medallist Dukurs was the clear winner in the men's singles skeleton on Friday, putting down two brilliant runs to win by a healthy margin of 0.79sec.
Germany's Alexander Gassner made a remarkable recovery after a first run to forget, going from ninth to first place at one point, but that was before Dukurs put down a second run that was even faster than his first.
Gassner had to share the second place with fellow German Felix Keisinger who was on course to take the silver outright but for a slight error towards the end of his second run, leaving them both on exactly the same time.
Tomass Dukurs, the race winner's older brother who's 40, finished fourth, dropping from second after his first run.
Matt Weston and Craig Thompson of Great Britain came fifth and sixth.
Janine Flock wins opening skeleton race
Janine Flock also won her opening race of the 2020-2021 IBSF World Cup season.
Runner up to PyeongChang silver medallist Jacqueline Loelling in the overall standings last term, Flock is out to go one better this time.
With 2018 Winter Olympic champ Lizzy Yarnold retired it will be fascinating to see who can take up the mantle as we near the Beijing 2022 Games.
Flock made a lightning-fast start, setting a new track record of 51.49 on her first run.
The Austrian claimed victory after two runs, 0.83s ahead of Netherland's Kimberley Bos, who claimed her best World Cup finish ever.
It was a fine result too for Endija Terauda of Latvia on her World Cup debut, coming home 1.40s from Flock's winning mark to take third.
The athletes will have some to recover as the next World Cup leg next week also happens here in Sigulda.