Mercedes Cup 2017: Steve Johnson, Mischa Zverev Advance in Monday's Play

Fifth seed Steve Johnson came back from a set down to beat Maximilian Marterer 3-6, 7-6 (2), 6-4 in the first round of the 2017 Mercedes Cup in Stuttgart, Germany, on Monday as the grass-court season got under way.

Sixth seed Mischa Zverev had an easier time of things as he booked himself a spot in the second round with a 6-3, 6-1 victory over Tunisia's Malek Jaziri. 

Meanwhile, German duo Jan-Lennard Struff and Yannick Hanfmann both enjoyed success as well with straight-sets victories over Lukas Lacko and Marton Fucsovics, respectively.

An updated schedule and full results can be found on the Pro Tennis Live app.

Roger Federer is the main attraction in Stuttgart this week, but the top seed has a bye into the second round, where he will play either Tommy Haas or Pierre-Hugues Herbert.

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The most significant action on Monday was Johnson's defeat of German Marterer, which for some time looked far from guaranteed.

The world No. 25 was broken twice in the first set to by Marterer, and after the pair both held six games apiece in the second, Johnson was left needing to win the tiebreak to stay in the competition.

He duly levelled the match up, winning the breaker 7-2, and crucially took the sole break of the decider—while giving up no chances on his own serve—to claim victory in 110 minutes.

World No. 31 Zverev looked very impressive as he swatted Jaziri aside. The German's serve was working wonderfully well and he did not concede a single break point in the entire match.

Jaziri, meanwhile, looked vulnerable from the off. He was competitive in the opener but was punished for his consistent inability to land his first serve, being broken twice.

It only got worse for the 33-year-old in the second set as he won just a single game, Zverev earning the win well inside an hour, per TennisTV:

Hanfmann's 6-3, 7-5 defeat of Hungarian Fucsovics was a fairly tight encounter, especially in the second set, but the German pounced at the right moments to seal victory in two sets.

Meanwhile, Struff's triumph over Lacko finished just shy of the 90-minute mark, with the 27-year-old running out the 6-4, 7-6 (3) winner after impressively saving all eight of the break points he conceded in the encounter.