At the moment, since Team Spirit went 8-0 in group stage and then beat Shopify 2-0 in the bracket decider, they are at a 10-game win streak at TI12. While impressive, long winning streaks are not uncommon at The international. Here's a brief overview of the longest winning streak at every TI, as far as I can tell.

The International 1

Na'Vi - 8 wins in a row - placed 1st

TI1 had very few total games played, so the 8 game win streak doesn't entirely convey how dominating Na'Vi was at this event. They open with 5 consecutive best-of-1 wins and a 2-0 in the upper bracket finals best-of-3, as well as getting a default win for the first game of the grand finals best-of-5. While they lost their second game, it's the only game they ever lost at this event. They setting the bar at an 8 game win streak.

The International 2

LGD - 19 wins in a row - placed 3rd

The longest streak on this list, LGD goes 14-0 in the group stage, and proceeds to sweep two best-of-3 series in the upper bracket as well as their first game in the upper bracket finals, until they ultimately lose their second game. They seem to lose momentum here and despite not making the grand finals, they made history by setting an insane 19 game win streak.

The International 3

Alliance - 17 wins in a row - placed 1st

Much like LGD the previous year Alliance goes 14-0 in the group stage. After this they sweep their first best-of-3, before winning the first game and losing the second game of a best-of-3 against Team DK. While LGD ended up losing two series after their streak, Alliance never lost a single series at this event, even if their streak ended at a 17 game win streak. Since Akke took place in the All-star match and won, he actually has an 18 game win streak at this event, while Loda's 17 game win streak was technically cut off at 14.

The International 4

Vici Gaming - 7 wins in a row - placed 2nd

EG - 7 wins in a row - placed 3rd

Vici Gaming and EG both win seven best-of-1 series in a row in the group stage, but don't manage to continue this streak after both losing other group stage games after this. Perhaps the least exciting streak on the list at a modest 7 game win streak for both teams, likely due to the strange format of the group stage.

The International 5

Vici Gaming - 9 wins in a row - placed 4th

Despite a disappointing group stage Vici Gaming proceeds to make a comeback by winning 8 games in a row in the lower bracket. Since they also won the last game of the group stage before this, they have the longest streak at this TI with a 9 game win streak.

The International 6

Fnatic - 9 wins in a row - placed 4th

Similar to Vici at TI5, Fnatic has a rough group stage, but wins their last three games of the group stage. They then proceed to win seven games in a row in the lower bracket, having the longest streak at TI6 at a 10 game win streak.

The International 7

LFY - 13 wins in a row - placed 3rd

While the three-game sweep in the grand finals by Liquid might be the most memorable streak of TI7, Liquid's longest winstreak at this event is only 5 games. LFY, however, dominated their group with an impressive 13 game win streak.

The International 8

PSG.LGD - 12 wins in a row - placed 2nd

PSG.LDG wins their last 8 games of the group stage and goes 2-0 in the first two upper bracket series. Unfortunately their next series was started with a loss against OG, stopping their momentum at 12 wins in a row.

The International 9

OG - 12 wins in a row - placed 1st

The defending champions come in strong in this tournament with OG only losing their second and second-to-last games of the group stage but winning everything in between, making for a 12-game win streak followed by their upper bracket run where they don't lose a single series at this event.

As far as memorable streaks go at TI9, Liquid's 9 game winstreak in the lower bracket has to be mentioned. To any Liquid fan this lower bracket run to the grand finals is a highly memorable 9 wins in a row. Upper bracket is for bitches.

The International 10

PDG.LGD - 12 wins in a row - placed 2nd

While Team Spirit ended up winning the event, their longest streak is only five games. With an 11 game win-streak in the group stage and winning the first game of the main event PSG.LGD was definitely the more dominating team early in the event. Their streak ended at 12 wins in a row, though they never lost a series until the grand finals.

The International 11

Tundra - 10 wins in a row - placed 1st

TI11 might remember Tundra as an unbeatable team, and their 10-game win streak across the group stage and early main event certainly shows that. Their streak is 10 games in a row, but were it not for their single loss against team Secret, their streak would be one of fourteen games and a faultless upper bracket run.

What does this mean for The International 12?

Team Spirit, as previously mentioned, sits at 10 wins in a row. Following this, assuming no more losses, they could add another 9 games (three best-of 3 series, one best-of-5). This means that if Spirit sweeps every single series in the main event they will tie LGD at 19 wins in a row.

Liquid only lost the first game of their group stage, which means they are only one game behind Spirit as far as streaks go, currently sitting at 9 and being able to reach 18 at most, unable to tie the record.

Since by definition all lower bracket teams lost their most recent game, the maximum streak any lower bracket team could hope for is 15 games by winning every remaining series until and including the grand final.

With the current TI format being as it is, no streak larger than 19 can achieved. Should we return to a format with two groups of ten teams each, the longest possible streak is 27 games in a row; 18 in group stage, and 9 during the main event. Despite this it seems likely that LGD's record in 2012 might never be broken.