Cologne - While the Bundesliga’s many stars continue to build up their fitness levels ahead of the new season, clubs up and down the country are working tirelessly behind the scenes to strengthen their playing staff in time for the big kick-off in August.

Over the next few weeks, bundesliga.com will be taking a closer look at each of the 18 top flight clubs’ summer transfer dealings so far, starting with Bundesliga new boys SV Darmstadt 98…

How they fared in 2014/15...

Having achieved promotion via the play-offs the previous season, not even the most optimistic of Darmstadt fans would have expected the Lilies to be rubbing shoulders with the likes of FC Bayern München, Borussia Dortmund and FC Schalke 04 within twelve months. That’s exactly what they’ll be doing in 2015/16, though, after finishing runners-up behind FC Ingolstadt 04 in Bundesliga 2 last term. "It’s like a dream," said winger Marcel Heller in May. "I still can’t describe it and I’m just so pleased that we’ve been promoted."

Ins…

Mario Vrancic (r.) (SC Paderborn 07)

  • 26-year-old attacking midfielder
  • Part of the Paderborn side that achieved promotion to the Bundesliga in 2013/14

What he offers: Exceptional work rate, strength in the tackle and an eye for goal

Konstantin Rausch (VfB Stuttgart)

  • 25-year-old Russian-born German left-back
  • 175 Bundesliga appearances for both Hannover 96 and Stuttgart

What he offers: Versatility, experience and a dangerous left foot

Jan Rosenthal (Eintracht Frankfurt)

  • German attacker, 29, signed from local rivals Frankfurt after a successful loan spell
  • 24 goals in 158 top-flight appearances for Frankfurt, Hannover and SC Freiburg

What he offers: Top-flight know-how, danger from set-pieces and the ability to arrive late into the box

Outs...

Romain Bregerie (r.) (FC Ingolstadt 04)

  • No-nonsense centre-back, 28
  • A vital part of the defence that achieved promotion last term, making 33 appearances and even chipping in with six goals

Hanno Behrens (1. FC Nürnberg)

  • 25-year-old defensive midfielder
  • 31 league appearances for the Lilies in 2013/14, scoring five times

Fabian Holland (Hertha Berlin)

  • 25-year-old left-back who has returned to parent club Hertha Berlin
  • Another key protagonist in Darmstadt’s promotion campaign, starting 25 of his 26 league outings last term

To-do list…

Rausch would appear to be an obvious like-for-like replacement for Holland in the left-back position, but the departure of centre-back Bregerie has left a sizeable void in the Lilies’ rearguard that Dirk Schuster (l.) has yet to fill this summer. At the other end of the pitch, last season’s top marksman Dominik Stroh-Engel will most likely share the goalscoring burden with Rosenthal, but having racked up just 12 league goals between them (Stroh-Engel 11, Rosenthal 1) last term, Schuster may still be looking to add another proven goalscorer to his squad.

Editor’s note: Not all summer transfers will be discussed here. The players featured in this article made at least ten league appearances for their respective clubs last season, chipped in with numerous goals and assists or made other significant contributions to their team. For an overview of the 2015/16 summer transfers, click here.