After the Swedish main army under Carl Johan Adlercreutz had won at the Battle of Alavus the newly appointed Russian commander, Nikolay Mikhailovich Kamensky, shifted his focus from the Swedish left—the Swedish force near Karstula under Otto von Fieandt—towards their center at Alavus, while only smaller contingents were ordered to engage the Swedish flanks;[2] von Fieandt was defeated at the Battle of Karstula by Yegor Vlastov, which brought an end to the Swedish hopes of holding the two-way intersection at Lintulaks; another Russian force under Colonel Koslov meanwhile marched to engage Carl von Otter on the Swedish right flank, at Nummijärvi (hardly two Scandinavian miles southeast of the Kauhajoki church).

The Swedes received him in a formation that crossed over the highway with its right flank protected by the Nummijärvi lake and the front by a small stream.

At 5:00 p.m. Koslov attacked along their whole line, but as he had left a significant number of troops in reserve the attack did not achieve enough weight to break through the Swedish lines, for which reason it stalled; von Otter then seized the initiative and counterattacked with his whole force and by 9:00 p.m. the Russians were forced to retreat.

Encouraged by Koslov's offensive, General Bibikov attacked the Swedish position at Lappfjärd the next day; however, as the Swedes received 3,000 reinforcements under Eberhard von Vegesack just earlier, Bibikov's force would run into a brick wall.

[1] The Swedes abandoned their position at Nummijärvi after the battle at Lappfjärd, as the 2nd Swedish division received orders from the Swedish headquarters to join up with the Swedish main army at Kuortane, in advance of the Battles of Salmi and Ruona; however, due to a series of conflicting orders and misunderstanding the 2nd division did not reach the Swedish main army in time before the battle—while the road junction at Kauhajoki was easily captured by Usjakov as the 150 defenders were forced to retreat with a loss of 25 men.