Goals from Joo Min-kyu and substitute Hwang Il-su saw Ulsan claim a 2-1 victory in the first leg at Saitama Stadium last week as the Korean team secured a first victory in eight away games on the Continent.

Two-time champions Urawa traditionally have a strong record at home in the knockout rounds but the loss leaves them with an uphill task ahead of the match at Ulsan Munsu Football Stadium.

Ulsan had not won away in the competition in more than two years but put in an assured performance at Saitama Stadium and, after falling behind, leveled before the interval through Joo Min-kyu before substitute Hwang Il-su struck a late winner. 

The victory means the Korean side now must only avoid defeat at home – where they have won all three of their games to date – to progress to the quarter-finals for the first time since winning the competition in 2012.

Moon Seon-min struck inside a minute in China to give two-time champions Jeonbuk a vital away goal but the Korean side were pegged back through Weng Shenchao’s equaliser shortly before the interval.

Hosts Jeonbuk have the slightest of advantages as they start the second leg at Jeonju World Cup Stadium knowing that a scoreless draw would see them progress to the quarter-finals for a ninth time.

The K league side are also unbeaten at home in the 2019 competition while Shanghai have yet to win on the road, although the Chinese champions have secured 2-2 and 3-3 draws away from home – results that would ensure they advance.

A first half strike from Wei Shihao and an own goal from Shandong defender Zheng Zheng sees Fabio Cannavaro's Guangzhou with a slim advantage ahead of the tie at Jinan Olympic Sports Center.

However, Zhang Chi's reply for Shandong does keep theings tantalisingly poised with the Jinan side returning to eastern China with an away goal from last week's visit to Tianhe Stadium.

Despite twice reaching the quarter-finals of the AFC Champions League, Shandong have still never managed a single victory in the knockout stages, drawing four and losing three of their seven games at this stage to date.

A week ago, Kashima snapped Sanfrecce's run of five consecutive AFC Champions League victories and the visitors come into the tie looking to progress to their third appearance in the quarter-finals.

A Serginho goal in the first leg was the difference for the 2018 winners, and it was a return to the kind of form the Brazilian showed in last year's campaign as the forward netted his sixth goal in seven knockout stage ties.

Sanfrecce, meanwhile, are looking to advance to the quarter final stage of the AFC Champions League for the very first time and they will be relying on their impressive home form.

All four of the last 16 ties are tantilisingly poised - either level or with a team holding a slim one goal advantage - and promise some rollercoaster action to come. The-AFC.com has picked out five things to look out for ahead of the games.

All four games remain tight ahead of the decisive return meetings in the coming days, before which the-AFC.com looks back at some of the numbers that caught the eye as the knockout rounds got underway.