Freiburg, meanwhile, have only lost once themselves in the opening five matches, but are searching for a first win since the opening day of the season.
Vincenzo Grifo gave Freiburg the lead with a superb curling finish from the left side of the penalty area, before good work from Max Kruse against his former club teed up Robert Andrich to equalise with a deflected effort from distance.
Streich's heart would have been in his mouth when Marvin Freidrich was presented with a glorious effort from close range late in the game. The 24-year-old centre-half has already scored twice this season and should have made it three to earn Union Berlin a deserved three points, but he headed narrowly wide.
Having failed to win since the opening day, Freiburg have now drawn three of their last four matches 1-1. While Streich will be determined to get back to winning ways, another draw against a Leverkusen side who will be expected to challenge for a top-four finish would be no bad result.
Indeed, Leverkusen's season appears to be up and running now having shown signs of teething problems without Kai Havertz and Kevin Volland, who were sold to Chelsea and Monaco respectively in the transfer window, in the early weeks of the campaign.
Last weekend's 3-1 win against Augsburg was impressive as it was exactly the type of game they have been regularly frustrated in under Peter Bosz in the past. Lucas Alario's first half penalty had given his side a deserved lead before Daniel Caligiuri levelled after the break.
As time progressed it looked like being another one of those days for Leverkusen, with Florian Wirtz's scuffed effort falling to Leon Bailey who struck the bar from close range, but Alario showed his calibre with a fine header from 12 yards before Moussa Diaby sealed the three points with an open goal after the opposition goalkeeper Rafal Gikiewicz had gone up for his side's corner in the last minute.
However, while that win took them into the top four for the first time this season, Bosz's side did stumble to a 1-0 defeat at Slavia Prague in the Europa League in midweek after Karim Bellarabi's first-half red card left them with a mountain to climb. There is still plenty of time to recover in that competition, though, with the league always the priority in any case.
Freiburg Bundesliga form: WDLDD
Freiburg form (all competitions): WWDLDD
Bayer Leverkusen Bundesliga form: DDDWW
Bayer Leverkusen form (all competitions): DDWWWL
The 55-year-old may look to bring in another defender or midfielder in an attempt to contain a Leverkusen side which thrives in possession, but equally will be wary of blunting his side's attacking impetus.
Bosz, meanwhile, is without Santiago Arias for the foreseeable future after the Colombian full-back's fibula fracture, with Paulinho also on the treatment table for some time after rupturing his cruciate ligament.
Striker Patrik Schick, however, is available for action once again after recovering from a torn muscle, but will likely have to remain patient from the bench given Alario's excellent form at present.
Freiburg possible starting lineup:
Muller; Schmid, Gulde, Lienhart, Heintz, Gunter; Sallai, Santamaria, Hofler, Grifo; Petersen
Bayer Leverkusen possible starting lineup:
Hradecky; L. Bender, S. Bender, Tapsoba, Sinkgraven; Palacios, Baumgartlinger, Amiri; Bailey, Alario, Diaby
We say: Freiburg 1-2 Bayer Leverkusen
We can envisage a narrow victory for Leverkusen, who appear to be hitting their stride and adjusting to life without Havertz and Volland. Freiburg's performances have not been particularly impressive in recent weeks, and while there is no doubting that they will make it difficult for the visitors, Bosz's side are showing signs of possessing a little more grit than in previous years.