Sahin arrived at the Santiago Bernabeu in the summer for €10million but is yet to make his Real debut after being hampered by a couple of injuries in pre-season.
However, Real coach Jose Mourinho recently revealed Sahin is on the right track in his bid to regain full fitness, and Alonso, who is expected to line up alongside the 23-year-old in midfield, admits he has been impressed by what he's seen so far in training.
"He [Sahin] has good attributes, a great left foot and he plays his football fast," Alonso told Radio Marca.
"He also has a great attitude, you can see he wants to integrate and wants so succeed.
"I'm waiting to play with him because he looks very good."
Real lost out in the La Liga title race to Barcelona last season, and were also eliminated by their bitter rivals in the UEFA Champions League semi-finals.
Mourinho's men did however beat Barca in the Copa del Rey final, but their only meeting so far this season has seen the Catalan side once again take the honours in a thrilling and hot-tempted two-legged Spanish Supercopa encounter.
Nonetheless, Alonso feels that Real, buoyed by the summer arrivals of Sahin, Fabio Coentrao, Hamit Altintop, Jose Callejon and Raphael Varane, can already stake a claim to being as good as Barca.
"In direct confrontations, we have been very close. Let's see if in the table we can get above them.
"In the Supercopa, we were at the same level without doubt.
"In the first-leg at home [which was a 2-2 draw], we were even the better side.
"Barca are a very good side and they have [Lionel] Messi. The key is to keep improving and not to become obsessed."
Barcelona are currently joint top in La Liga with surprise package Levante on 14 points, while Real are just a point behind in third.