EMC ( EMC) CEO Joe Tucci spent time playing semi-pro baseball as a young man and is clearly willing to play hardball in his dogged pursuit of Data Domain ( DDUP).

The Hopkinton, Mass.-based firm's battle with archrival NetApp ( NTAP) to buy Data Domain has become a bidding war.

As widely expected, Tucci and EMC upped the ante Monday, increasing their all-cash bid from $30 to $33.50 a share. If approved, the deal would be worth $2.1 billion to Data Domain shareholders, significantly more than previous offers from both EMC and NetApp.

Investors are now monitoring the situation to see whether NetApp will pony up yet more money, or concede defeat to its cash-rich foe.

Data Domain's board clinched a $1.9 billion cash and stock deal with NetApp last month, citing the good cultural fit between the two companies. This followed a $1.9 billion all-cash bid from EMC, which in turn surpassed NetApp's prior offer of $1.5 billion in cash and stock.

"If Data Domain pushes away EMC again, I think they will owe their shareholders an explanation for why they rejected an offer, that, on paper, was superior," said Charles King, principal analyst at technology research firm Pund-IT.

Undeterred by last month's Data Domain-NetApp deal, Tucci recently launched a charm offensive aimed at Data Domain's 800-plus employees, and is now putting his money where his mouth is.

Crucially, EMC is also proposing a whirlwind acquisition with no break-up fees. In a statement released Monday, the storage behemoth said that it could close the transaction in as little as two weeks, almost a month faster than NetApp.

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